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Sample records for small-angle neutron scatter

  1. Small Angle Neutron Scattering

    SciTech Connect

    Urban, Volker S

    2012-01-01

    Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

  2. Small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Cousin, Fabrice

    2015-10-01

    Small Angle Neutron Scattering (SANS) is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ˜ 1 nm up to ˜ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ˜ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area…) through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons) make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer), form factor analysis (I(q→0), Guinier regime, intermediate regime, Porod regime, polydisperse system), structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates), and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast). It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of spectrometer

  3. Fractal Approach in Petrology: Combining Ultra-Small Angle (USANA) and Small Angle Neutron Scattering (SANS)

    SciTech Connect

    LoCelso, F.; Triolo, F.; Triolo, A.; Lin, J.S.; Lucido, G.; Triolo, R.

    1999-10-14

    Ultra small angle neutron scattering instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering instruments on one side and optical microscopy on the other side. Rocks showing fractal behavior in over two decades of momentum transfer and seven orders of magnitude of intensity are examined and fractal parameters are extracted from the combined USANS and SANS curves.

  4. Small-angle neutron scattering from samples of expanded carbon

    SciTech Connect

    Bogdanov, S. G. Valiev, E. Z.; Dorofeev, Yu. A.; Pirogov, A. N.; Skryabin, Yu. N.; Makotchenko, V. G.; Nazarov, A. S.; Fedorov, V. E.

    2006-12-15

    The subatomic structure of expanded graphite has been investigated by small-angle neutron scattering. Samples were synthesized during quick thermal decomposition of intercalated compounds based on oxidized graphite. They had a low bulk density (up to 0.1 g/cm{sup 3}) and were characterized by considerable small-angle scattering. It has been established that majority of the volume of expanded graphite samples is occupied by participles with characteristic sizes in two ranges: from 6 to 8 nm and from 20 to 30 nm. Small particles have properties of a surface fractal with the dimension D{sub s} = 2.4-2.6, whereas the larger particles are mainly smooth and have the dimension D{sub s} = 2.0-2.1. The specific surface of the samples studied was determined from the small-angle scattering data.

  5. SANS (small-angle neutron scattering) from polymers and colloids

    SciTech Connect

    Hayter, J.B.

    1987-01-01

    Small-angle neutron scattering (SANS) has been remarkably successful in providing detailed quantitative structural information on complex everyday materials, such as polymers and colloids, which are often of considerable industrial as well as academic interest. This paper reviews some recent SANS experiments on polymers and colloids, including ferrofluids, and discusses the use of these apparently complex systems as general physical models of the liquid or solid state.

  6. ASIC for Small Angle Neutron Scattering Experiments at the SNS

    NASA Astrophysics Data System (ADS)

    De Geronimo, Gianluigi; Fried, Jack; Smith, Graham C.; Yu, Bo; Vernon, Emerson; Britton, Charles L.; Bryan, William L.; Clonts, Lloyd G.; Frank, Shane S.

    2007-06-01

    We present an ASIC for a 3He gas detector to be used in small angle neutron scattering experiments at the spallation neutron source in oak ridge. The ASIC is composed of 64 channels with low noise charge amplification, filtering, timing and amplitude measurement circuits, where an innovative current-mode peak-detector and digitizer (PDAD) is adopted. The proposed PDAD provides at the same time peak detection and A/D conversion in real time, at low power, and without requiring a clock signal. The channels share an efficient data sparsification and derandomization scheme, a 30-bit 256 deep FIFO, and low voltage differential signaling.

  7. A novel small-angle neutron scattering detector geometry

    PubMed Central

    Kanaki, Kalliopi; Jackson, Andrew; Hall-Wilton, Richard; Piscitelli, Francesco; Kirstein, Oliver; Andersen, Ken H.

    2013-01-01

    A novel 2π detector geometry for small-angle neutron scattering (SANS) applications is presented and its theoretical performance evaluated. Such a novel geometry is ideally suited for a SANS instrument at the European Spallation Source (ESS). Motivated by the low availability and high price of 3He, the new concept utilizes gaseous detectors with 10B as the neutron converter. The shape of the detector is inspired by an optimization process based on the properties of the conversion material. Advantages over the detector geometry traditionally used on SANS instruments are discussed. The angular and time resolutions of the proposed detector concept are shown to satisfy the requirements of the particular SANS instrument. PMID:24046504

  8. Small-angle neutron scattering study of polymeric micellar structures

    SciTech Connect

    Wu, G.; Chu, B. ); Schneider, D.K. )

    1994-11-17

    Polymeric micellar structures formed by a PEO-PPO-PEO copolymer in o-xylene in the presence of water were investigated by small-angle neutron scattering. In order to reveal the detailed micellar structure, different contrasts among the micellar core, the micellar shell, and the dispersing medium (background) were constructed by selectively changing the protonated/deuterated combination of water and xylene. The micellar structure could be well described by a core-shell structure with the scattering behavior of the micellar shell being very similar to that of a star polymer. The solubilized water existed not only in the micellar core but also in the micellar shell. The volume fraction of a copolymer segments in the micellar shell was rather low, being of the order of 0.2. There seemed to be no sharp interface between the micellar core and the micellar shell. 25 refs., 11 figs., 4 tabs.

  9. Small angle neutron scattering using a triple axis spectrometer

    SciTech Connect

    Ahmend, F.U.; Kamal, I.; Yunus, S.M.

    1994-12-31

    SANS technique has been developed on a triple axis neutron spectrometer at TRIGA Mark II (3 MW) research reactor, AERE, Savar, Dhaka, Bangladesh. Double crystal (with very small mosaic spread {approximately} 1 min.) diffraction known as Bonse and Hart`s method has been employed in this technique. Such a device is a useful tool for small angle scattering in the Q range between 10{sup -5} and 10{sup -1} {Angstrom}{sup -1} and for real time experiments at short time scales. Therefore, large objects and large distance interparticle correlations can be investigated easily by this method. Test measurements using alumina (Al{sub 2}O{sub 3}) sample has been carried out to exploit this method. The radius of gyration has been determined and the data has been fitted to the scattering function of a sphere.

  10. Small angle neutron scattering studies of vesicle stability

    SciTech Connect

    Mang, J.T.; Hjelm, R.P.

    1997-10-01

    Small angle neutron scattering (SANS) was used to investigate the structure of mixed colloids of egg yolk phosphatidylcholine (EYPC) with the bile salt, cholylglycine (CG), in D{sub 2}O as a function of pressure (P) and temperature (T). At atmospheric pressure, the system forms an isotropic phase of mixed, single bilayer vesicles (SLV`s). Increasing the external hydrostatic pressure brought about significant changes in particle morphology. At T = 25 C, application of a pressure of 3.5 MPa resulted in the collapse of the SLV`s. Further increase of P, up to 51.8 MPa, resulted in a transition from a phase of ordered (stacked), collapsed vesicles to one of stacked, ribbon-like particles. A similar collapse of the vesicles was observed at higher temperature (T = 37 C) with increasing P, but at this temperature, no ribbon phase was found at the highest pressure explored.

  11. Radiation damage study using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Rétfalvi, E.; Török, Gy; Rosta, L.

    2000-03-01

    Nuclear radiation provides important changes in the microstructure of metallic components of nuclear power plant and research reactors, influencing their mechanical properties. The investigation of this problem has primary interest for the safety and life-time of such nuclear installations. For the characterization of this kind of nanostructures small angle neutron scattering technique is a very useful tool. We have carried out experiments on samples of irradiated reactor vessel material and welded components of VVER-440-type reactors on the SANS instrument at the Budapest Research Reactor. In our measurements irradiated as well as non-irradiated samples were compared and magnetic field was applied for viewing the magnetic structure effects of the materials. A clear modification of the structure due to irradiation was obtained. Our data were analyzed by the ITP92 code, the inverse Fourier transform program of O. Glatter [1].

  12. Characterization of photosynthetic supramolecular assemblies using small angle neutron scattering

    SciTech Connect

    Tiede, D.M.; Marone, P.; Wagner, A.M.; Thiyagarajan, P.

    1995-12-31

    We are using small angle neutron scattering (SANS) to resolve structural features of supramolecular assemblies of photosynthetic proteins in liquid and frozen solutions. SANS resolves the size, shape, and structural homogeneity of macromolecular assemblies in samples identical to those used for spectroscopic assays of photosynthetic function. Likely molecular structures of the supramolecular assemblies can be identified by comparing experimental scattering data with scattering profiles calculated for model supramolecular assemblies built from crystal structures of the individual proteins. SANS studies of the Rhodobacter sphaeroides reaction center, RC, presented here, show that the detergent solubilized RC exists in a variety of monomeric and aggregation states. The distribution between monomer and aggregate was found to depend strongly upon detergent, temperature and nature of additives, such as ethylene glycol used for low temperature spectroscopy and polyethylene glycol used for crystallization. Likely aggregate structures are being identified by fitting the experimental scattering profiles with those calculated for model aggregates built-up using the RC crystal structure. This work establishes the foundation for using SANS to identify intermediates in the RC crystallization pathways, and for determining likely structures of complexes formed between the RC and its physiological reaction partners, cytochrome c, and the LHI antenna complex.

  13. Ultra-small-angle neutron scattering with azimuthal asymmetry.

    PubMed

    Gu, X; Mildner, D F R

    2016-06-01

    Small-angle neutron scattering (SANS) measurements from thin sections of rock samples such as shales demand as great a scattering vector range as possible because the pores cover a wide range of sizes. The limitation of the scattering vector range for pinhole SANS requires slit-smeared ultra-SANS (USANS) measurements that need to be converted to pinhole geometry. The desmearing algorithm is only successful for azimuthally symmetric data. Scattering from samples cut parallel to the plane of bedding is symmetric, exhibiting circular contours on a two-dimensional detector. Samples cut perpendicular to the bedding show elliptically dependent contours with the long axis corresponding to the normal to the bedding plane. A method is given for converting such asymmetric data collected on a double-crystal diffractometer for concatenation with the usual pinhole-geometry SANS data. The aspect ratio from the SANS data is used to modify the slit-smeared USANS data to produce quasi-symmetric contours. Rotation of the sample about the incident beam may result in symmetric data but cannot extract the same information as obtained from pinhole geometry.

  14. Ultra-small-angle neutron scattering with azimuthal asymmetry

    PubMed Central

    Gu, X.; Mildner, D. F. R.

    2016-01-01

    Small-angle neutron scattering (SANS) measurements from thin sections of rock samples such as shales demand as great a scattering vector range as possible because the pores cover a wide range of sizes. The limitation of the scattering vector range for pinhole SANS requires slit-smeared ultra-SANS (USANS) measurements that need to be converted to pinhole geometry. The desmearing algorithm is only successful for azimuthally symmetric data. Scattering from samples cut parallel to the plane of bedding is symmetric, exhibiting circular contours on a two-dimensional detector. Samples cut perpendicular to the bedding show elliptically dependent contours with the long axis corresponding to the normal to the bedding plane. A method is given for converting such asymmetric data collected on a double-crystal diffractometer for concatenation with the usual pinhole-geometry SANS data. The aspect ratio from the SANS data is used to modify the slit-smeared USANS data to produce quasi-symmetric contours. Rotation of the sample about the incident beam may result in symmetric data but cannot extract the same information as obtained from pinhole geometry. PMID:27275140

  15. Ultra-small-angle neutron scattering with azimuthal asymmetry

    SciTech Connect

    Gu, X.; Mildner, D. F. R.

    2016-05-16

    Small-angle neutron scattering (SANS) measurements from thin sections of rock samples such as shales demand as great a scattering vector range as possible because the pores cover a wide range of sizes. The limitation of the scattering vector range for pinhole SANS requires slit-smeared ultra-SANS (USANS) measurements that need to be converted to pinhole geometry. The desmearing algorithm is only successful for azimuthally symmetric data. Scattering from samples cut parallel to the plane of bedding is symmetric, exhibiting circular contours on a two-dimensional detector. Samples cut perpendicular to the bedding show elliptically dependent contours with the long axis corresponding to the normal to the bedding plane. A method is given for converting such asymmetric data collected on a double-crystal diffractometer for concatenation with the usual pinhole-geometry SANS data. Furthermore, the aspect ratio from the SANS data is used to modify the slit-smeared USANS data to produce quasi-symmetric contours. Rotation of the sample about the incident beam may result in symmetric data but cannot extract the same information as obtained from pinhole geometry.

  16. Ultra-small-angle neutron scattering with azimuthal asymmetry

    DOE PAGES

    Gu, X.; Mildner, D. F. R.

    2016-05-16

    Small-angle neutron scattering (SANS) measurements from thin sections of rock samples such as shales demand as great a scattering vector range as possible because the pores cover a wide range of sizes. The limitation of the scattering vector range for pinhole SANS requires slit-smeared ultra-SANS (USANS) measurements that need to be converted to pinhole geometry. The desmearing algorithm is only successful for azimuthally symmetric data. Scattering from samples cut parallel to the plane of bedding is symmetric, exhibiting circular contours on a two-dimensional detector. Samples cut perpendicular to the bedding show elliptically dependent contours with the long axis corresponding tomore » the normal to the bedding plane. A method is given for converting such asymmetric data collected on a double-crystal diffractometer for concatenation with the usual pinhole-geometry SANS data. Furthermore, the aspect ratio from the SANS data is used to modify the slit-smeared USANS data to produce quasi-symmetric contours. Rotation of the sample about the incident beam may result in symmetric data but cannot extract the same information as obtained from pinhole geometry.« less

  17. New Very Small Angle Neutron Scattering (VSANS) Instrument

    NASA Astrophysics Data System (ADS)

    Van Every, E.; Deyhim, A.; Kulesza, J.

    2016-09-01

    The design of a new Very Small Angle Neutron Scattering (VSANS) Instrument for use in National Institute of Standards And Technology (NIST) will be discussed. This instrument is similar to a shorter instrument we designed and delivered to ANSTO in Australia called the Bilby SANS instrument. The NIST VSANS and the ANSTO Bilby SANS instruments have very similar dimensions for length and diameter and have similar requirements for internal detector motion, top access port, walkway supports, and ports; however, the Bilby SANS instrument vacuum requirement was lower (7.5×10-5 Torr) and the entire (60,000 pound) vessel was required to move 1.5 meters on external rails with a repeatability of 100 um, which ADC achieved. The NIST VSANS length is 24 meter, internal diameter 2.3 meter with three internal carriages. The NIST VSANS instrument, which covers the usual SANS range will also allow configuration to cover the range between q ∼⃒ 10-4 A-1 to 10-3 A-1 with a sample beam current of (104 neutrons/s). The key requirements are a second position-sensitive detector system having a 1 mm pixel size and a longer sample-detector flight path of 20 m (i.e., a 40 m instrument).

  18. Multiple small angle neutron scattering: A new two-dimensional ultrasmall angle neutron scattering technique

    SciTech Connect

    Gruenzweig, C.; Hils, T.; Muehlbauer, S.; Ay, M.; Lorenz, K.; Georgii, R.; Gaehler, R.; Boeni, P.

    2007-11-12

    We report on the demonstration experiment of the multiple small angle neutron scattering (MSANS) technique at a 5.6 m long neutron beam line, leading to a q resolution of 3x10{sup -4} A{sup -1}. The MSANS technique is based on two two-dimensional multihole apertures placed at the front end of the collimator and close to the sample, respectively. By choosing the proper MSANS geometry, individual diffraction patterns are superimposed leading to a large gain in intensity. Using MSANS as an option for standard small angle neutron scattering beam lines, the q resolution could be increased to 10{sup -5} A{sup -1} without dramatically sacrificing intensity.

  19. Heparin's solution structure determined by small-angle neutron scattering.

    PubMed

    Rubinson, Kenneth A; Chen, Yin; Cress, Brady F; Zhang, Fuming; Linhardt, Robert J

    2016-12-01

    Heparin is a linear, anionic polysaccharide that is widely used as a clinical anticoagulant. Despite its discovery 100 years ago in 1916, the solution structure of heparin remains unknown. The solution shape of heparin has not previously been examined in water under a range of concentrations, and here is done so in D2 O solution using small-angle neutron scattering (SANS). Solutions of 10 kDa heparin-in the millimolar concentration range-were probed with SANS. Our results show that when sodium concentrations are equivalent to the polyelectrolyte's charge or up to a few hundred millimoles higher, the molecular structure of heparin is compact and the shape could be well modeled by a cylinder with a length three to four times its diameter. In the presence of molar concentrations of sodium, the molecule becomes extended to nearly its full length estimated from reported X-ray measurements on stretched fibers. This stretched form is not found in the presence of molar concentrations of potassium ions. In this high-potassium environment, the heparin molecules have the same shape as when its charges were mostly protonated at pD ≈ 0.5, that is, they are compact and approximately half the length of the extended molecules.

  20. Multiple magnetic scattering in small-angle neutron scattering of Nd–Fe–B nanocrystalline magnet

    PubMed Central

    Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta

    2016-01-01

    We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd–Fe–B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd–Fe–B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd–Fe–B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters. PMID:27321149

  1. Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet.

    PubMed

    Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P; Keiderling, Uwe; Ono, Kanta

    2016-06-20

    We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.

  2. Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet

    NASA Astrophysics Data System (ADS)

    Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta

    2016-06-01

    We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.

  3. Spin echo small angle neutron scattering using a continuously pumped {sup 3}He neutron polarisation analyser

    SciTech Connect

    Parnell, S. R.; Li, K.; Yan, H.; Stonaha, P.; Li, F.; Wang, T.; Baxter, D. V.; Snow, W. M.; Washington, A. L.; Walsh, A.; Chen, W. C.; Parnell, A. J.; Fairclough, J. P. A.; Pynn, R.

    2015-02-15

    We present a new instrument for spin echo small angle neutron scattering (SESANS) developed at the Low Energy Neutron Source at Indiana University. A description of the various instrument components is given along with the performance of these components. At the heart of the instrument are a series of resistive coils to encode the neutron trajectory into the neutron polarisation. These are shown to work well over a broad range of neutron wavelengths. Neutron polarisation analysis is accomplished using a continuously operating neutron spin filter polarised by Rb spin-exchange optical pumping of {sup 3}He. We describe the performance of the analyser along with a study of the {sup 3}He polarisation stability and its implications for SESANS measurements. Scattering from silica Stöber particles is investigated and agrees with samples run on similar instruments.

  4. Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

    NASA Astrophysics Data System (ADS)

    Du, Rong; Tian, Haolai; Zuo, Taisen; Tang, Ming; Yan, Lili; Zhang, Junrong

    2017-09-01

    Small-angle neutron scattering (SANS) is an experimental technique to detect material structures in the nanometer to micrometer range. The solution of the structural model constructed from SANS strongly depends on the accuracy of the reduced data. The time-of-flight (TOF) SANS data are dependent on the wavelength of the pulsed neutron source. Therefore, data reduction must be handled very carefully to transform measured neutron events into neutron scattering intensity. In this study, reduction algorithms for TOF SANS data are developed and optimized using simulated data from a virtual neutron experiment. Each possible effect on the measured data is studied systematically, and suitable corrections are performed to obtain high-quality data. This work will facilitate scientific research and the instrument design at China Spallation Neutron Source.

  5. Experimental methods in the study of neutron scattering at small angles

    SciTech Connect

    Dragolici, Cristian A.

    2014-11-24

    Small angle scattering (SAS) is the collective name given to the techniques of small angle neutron (SANS) and X-ray (SAXS) scattering. They offer the possibility to analyze particles without disturbing their natural environment. In each of these techniques radiation is elastically scattered by a sample and the resulting scattering pattern is analyzed to provide information about the size, shape and orientation of some component of the sample. Accordingly, a large number of methods and experimental patterns have been developed to ease the investigation of condensed matter by use of these techniques. Some of them are the discussed in this paper.

  6. Small Angle Neutron Scattering at the National Institute of Standards and Technology

    PubMed Central

    Hammouda, B.; Krueger, S.; Glinka, C. J.

    1993-01-01

    The small angle neutron scattering technique is a valuable method for the characterization of morphology of various materials. It can probe inhomogeneities in the sample (whether occurring naturally or introduced through isotopic substitution) at a length scale from the atomic size (nanometers) to the macroscopic (micrometers) size. This work provides an overview of the small angle neutron scattering facilities at the National Institute of Standards and Technology and a review of the technique as it has been applied to polymer systems, biological macromolecules, ceramic, and metallic materials. Specific examples have been included. PMID:28053456

  7. Informing the improvement of forest products durability using small angle neutron scattering

    Treesearch

    Nayomi Plaza-Rodriguez; Sai Venkatesh Pingali; Shuo Qian; William T. Heller; Joseph E. Jakes

    2016-01-01

    A better understanding of how wood nanostructure swells with moisture is needed to accelerate the development of forest products with enhanced moisture durability. Despite its suitability to study nanostructures, small angle neutron scattering (SANS) remains an underutilized tool in forest products research. Nanoscale moisture-induced structural changes in intact and...

  8. Development and prospects of Very Small Angle Neutron Scattering (VSANS) techniques

    NASA Astrophysics Data System (ADS)

    Xuo, Tai-Sen; Cheng, He; Chen, Yuan-Bo; Wang, Fang-Wei

    2016-07-01

    Very Small Angle Neutron Scattering (VSANS) is an upgrade of the traditional Small Angle Neutron Scattering (SANS) technique which can cover three orders of magnitude of length scale from one nanometer to one micrometer. It is a powerful tool for structure calibration in polymer science, biology, material science and condensed matter physics. Since the first VSANS instrument, D11 in Grenoble, was built in 1972, new collimation techniques, focusing optics (multi-beam converging apertures, material or magnetic lenses, and focusing mirrors) and higher resolution detectors combined with the long flight paths and long incident neutron wavelengths have been developed. In this paper, a detailed review is given of the development, principles and application conditions of various VSANS techniques. Then, beam current gain factors are calculated to evaluate those techniques. A VSANS design for the China Spallation Neutron Source (CSNS) is thereby presented. Supported by National Natural Science Foundation of China (21474119, 11305191)

  9. Survey of background scattering from materials found in small-angle neutron scattering

    PubMed Central

    Barker, J. G.; Mildner, D. F. R.

    2015-01-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300–700 K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scattering from solids. Background from the residual air in detector vacuum vessels and scattering from the 3He detector dome are presented. The thickness dependence of the multiple scattering correction for forward scattering from water is calculated. Inelastic phonon background scattering at small angles for crystalline solids is both modeled and compared with measurements. Methods of maximizing the signal-to-noise ratio by material selection, choice of sample thickness and wavelength, removal of inelastic background by TOF or Be filters, and removal of spin-flip scattering with polarized beam analysis are discussed. PMID:26306088

  10. Survey of background scattering from materials found in small-angle neutron scattering.

    PubMed

    Barker, J G; Mildner, D F R

    2015-08-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300-700 K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a (3)He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scattering from solids. Background from the residual air in detector vacuum vessels and scattering from the (3)He detector dome are presented. The thickness dependence of the multiple scattering correction for forward scattering from water is calculated. Inelastic phonon background scattering at small angles for crystalline solids is both modeled and compared with measurements. Methods of maximizing the signal-to-noise ratio by material selection, choice of sample thickness and wavelength, removal of inelastic background by TOF or Be filters, and removal of spin-flip scattering with polarized beam analysis are discussed.

  11. Solution properties of a CO{sub 2}-soluble fluoropolymer via small angle neutron scattering

    SciTech Connect

    McClain, J.B.; Combes, J.R.; Romack, T.J.; Canelas, D.A.; Betts, D.E.; Samulski, E.T.; DeSimone, J.M.; Londono, D.; Wignall, G.D.

    1996-01-31

    In this communication, we report the first characterization of solutions of a high molecular weight polymer in supercritical CO{sub 2} by small-angle neutron scattering (SANS). It is shown that small-angle neutron scattering gives key molecular parameters of an amorphous fluoropolymer in supercritical CO{sub 2}, i.e., the molecular weight, radius of gyration, and second virial coefficient, and thereby gives insights into a polymer chain`s behavior in this unique solvent. The positive sign of the second virial coefficients indicate that this medium is a good solvent - there is no evidence of a collapsed chain conformation. In fact, we conclude from the SANS data that, in CO{sub 2}, the poly(FOA) chain dimensions are expanded relative to those characteristic of its melt. 29 refs., 2 figs., 1 tab.

  12. Two-dimensional position-sensitive detectors for small-angle neutron scattering

    SciTech Connect

    McElhaney, S.A.; Vandermolen, R.I.

    1990-05-01

    In this paper, various detectors available for small angle neutron scattering (SANS) are discussed, along with some current developments being actively pursued. A section has been included to outline the various methodologies of position encoding/decoding with discussions on trends and limitations. Computer software/hardware vary greatly from institute and experiment and only a general discussion is given to this area. 85 refs., 33 figs.

  13. A neutron detector to monitor the intensity of transmitted neutrons for small-angle neutron scattering instruments

    NASA Astrophysics Data System (ADS)

    De Lurgio, Patrick M.; Klann, Raymond T.; Fink, Charles L.; McGregor, Douglas S.; Thiyagarajan, Pappannan; Naday, Istvan

    2003-06-01

    A semiconductor-based neutron detector was developed at Argonne National Laboratory (ANL) for use as a neutron beam monitor for small-angle neutron scattering instruments. The detector is constructed using a coating of 10B on a gallium-arsenide semiconductor detector and is mounted directly within a cylindrical (2.2 cm dia. and 4.4 cm long) enriched 10B 4C beam stop in the time-of-flight Small Angle Neutron Diffractometer (SAND) instrument at the Intense Pulsed Neutron Source (IPNS) facility at ANL. The neutron beam viewed by the SAND is from a pulsed spallation source moderated by a solid methane moderator that produces useful neutrons in the wavelength range of 0.5-14 Å. The SAND instrument uses all detected neutrons in the above wavelength range sorted by time-of-flight into 68 constant Δ T/ T=0.05 channels. This new detector continuously monitors the transmitted neutron beam through the sample during scattering measurements and takes data concurrently with the other detectors in the instrument. The 10B coating on the GaAs detector allows the detection of the cold neutron spectrum with reasonable efficiency. This paper describes the details of the detector fabrication, the beam stop monitor design, and includes a discussion of results from preliminary tests using the detector during several run cycles at the IPNS.

  14. Small-angle neutron scattering studies from solutions of bovine nasal cartilage proteoglycan

    SciTech Connect

    Patel, A.; Stivala, S.S.; Damle, S.P.; Gregory, J.D.; Bunick, G.J.; Uberbacher, E.C.

    1985-08-01

    Small-angle neutron scattering, SANS, of the proteoglycan subunit of bovine nasal cartilage in 0.15N LiCl at 25/sup 0/C yielded the radius of gyration, R/sub g/, radius of gyration of the cross-section, R/sub q/, persistence length, a, and the molecular weight, M. The following values were obtained: M = 3.9 x 10/sup 6/, R/sub g/ = 745 A, R/sub q/ = 34.6 A and a = 35.2 A. These values compare favorably with those that were obtained from small angle x-ray scattering, SAXS, of a similar extract. The scattering curve of the proteoglycan subunit in D/sub 2/O showed a characteristic broad peak in the specified angular range similar to that observed from SAXS, thus confirming the polyelectrolyte nature of the proteoglycan. 15 refs., 3 figs., 1 tab. (DT)

  15. Characterization of porous materials using combined small-angle X-ray and neutron scattering techniques

    SciTech Connect

    Hu, Naiping; Borkar, Neha; Kohls, Doug; Schaefer, Dale W.

    2014-09-24

    A combination of ultra small angle X-ray scattering (USAXS) and ultra small angle neutron scattering (USANS) is used to characterize porous materials. The analysis methods yield quantitative information, including the mean skeletal chord length, mean pore chord length, skeletal density, and composition. A mixed cellulose ester (MCE) membrane with a manufacturer-labeled pore size of 0.1 {mu}m was used as a model to elucidate the specifics of the method. Four approaches describing four specific scenarios (different known parameters and form of the scattering data) are compared. Pore chords determined using all four approaches are in good agreement with the scanning electron microscopy estimates but are larger than the manufacturer's nominal pore size. Our approach also gives the average chord of the skeletal solid (struts) of the membrane, which is also consistent for all four approaches. Combined data from USAXS and USANS gives the skeletal density and the strut composition.

  16. A small angle neutron scattering study of mica based glass-ceramics with applications in dentistry

    NASA Astrophysics Data System (ADS)

    Kilcoyne, S. H.; Bentley, P. M.; Al-Jawad, M.; Bubb, N. L.; Al-Shammary, H. A. O.; Wood, D. J.

    2004-07-01

    We are currently developing machinable and load-bearing mica-based glass-ceramics for use in restorative dental surgery. In this paper we present the results of an ambient temperature small angle neutron scattering (SANS) study of several such ceramics with chemical compositions chosen to optimise machinability and strength. The SANS spectra are all dominated by scattering from the crystalline-amorphous phase interface and exhibit Q-4 dependence (Porod scattering) indicating that, on a 100Å scale, the surface of the crystals is smooth.

  17. Structured water in polyelectrolyte dendrimers: Understanding small angle neutron scattering results through atomistic simulation

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Kerkeni, Boutheïna; Egami, Takeshi; Do, Changwoo; Liu, Yun; Wang, Yongmei; Porcar, Lionel; Hong, Kunlun; Smith, Sean C.; Liu, Emily L.; Smith, Gregory S.; Chen, Wei-Ren

    2012-04-01

    Based on atomistic molecular dynamics (MD) simulations, the small angle neutron scattering (SANS) intensity behavior of a single generation-4 polyelectrolyte polyamidoamine starburst dendrimer is investigated at different levels of molecular protonation. The SANS form factor, P(Q), and Debye autocorrelation function, γ(r), are calculated from the equilibrium MD trajectory based on a mathematical approach proposed in this work. The consistency found in comparison against previously published experimental findings (W.-R. Chen, L. Porcar, Y. Liu, P. D. Butler, and L. J. Magid, Macromolecules 40, 5887 (2007)) leads to a link between the neutron scattering experiment and MD computation, and fresh perspectives. The simulations enable scattering calculations of not only the hydrocarbons but also the contribution from the scattering length density fluctuations caused by structured, confined water within the dendrimer. Based on our computational results, we explore the validity of using radius of gyration RG for microstructure characterization of a polyelectrolyte dendrimer from the scattering perspective.

  18. Orienting rigid and flexible biological assemblies in ferrofluids for small-angle neutron scattering studies

    PubMed Central

    Sosnick, T.; Charles, S.; Stubbs, G.; Yau, P.; Bradbury, E. M.; Timmins, P.; Trewhella, J.

    1991-01-01

    Small-angle scattering from macromolecules in solution is widely used to study their structures, but the information content is limited because the molecules are generally randomly oriented and hence the data are spherically averaged. The use of oriented rodlike structures for scattering, as in fiber diffraction, greatly increases the amount of structural detail that can be obtained. A new technique using a ferromagnetic fluid has been developed to align elongated structures independent of their intrinsic magnetic properties. This technique is ideal for small-angle neutron scattering because the scattering from the ferrofluid particles can be reduced significantly by matching the neutron scattering length density of the particles to a D2O solvent (“contrast matching”). The net result is scattering primarily from the ordered biological assembly in a solution environment that can be adjusted to physiological pH and ionic strength. Scattering results from ordered tobacco mosaic virus, tobacco rattle virus, and chromain fibers are presented. ImagesFIGURE 4FIGURE 4 PMID:19431809

  19. Equilibrium polymerization of liquid sulphur from small angle neutron scattering of sulphur solutions

    NASA Astrophysics Data System (ADS)

    Boué, F.; Ambroise, J. P.; Bellissent, R.; Pfeuty, P.

    1992-06-01

    The reversible singular anomaly which shows up in liquid sulphur at 159°C and is also present in sulphur solutions has been clearly detected for the first time by small angle neutron scattering in solutions of sulphur with deuterated naphtalene and of sulphur with deuterated biphenyl. The observed sudden rise of the small q limit of the scattering intensity is interpreted as the signature of an equilibrium polymerization transition with formation of long sulphur chains. Experimental meausrements are in qualitative agreement with theoretical predictions based on the mean field approximation of a lattice model.

  20. Microstructural investigations on Russian reactor pressure vessel steels by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Ulbricht, A.; Boehmert, J.; Strunz, P.; Dewhurst, C.; Mathon, M.-H.

    The effect of radiation embrittlement has a high safety significance for Russian VVER reactor pressure vessel steels. Heats of base and weld metals of the as-received state, irradiated state and post-irradiation annealed state were investigated using small-angle neutron scattering (SANS) to obtain insight about the microstructural features caused by fast neutron irradiation. The SANS intensities increase in the momentum transfer range between 0.8 and 3 nm-1 for all the material compositions in the irradiated state. The size distribution function of the irradiation-induced defect clusters has a pronounced maximum at 1 nm in radius. Their content varies between 0.1 and 0.7 vol.% dependent on material composition and increases with the neutron fluence. The comparison of nuclear and magnetic scattering indicates that the defects differ in their composition. Thermal annealing reduces the volume fraction of irradiation defect clusters.

  1. Wavelength-independent constant period spin-echo modulated small angle neutron scattering

    SciTech Connect

    Sales, Morten; Plomp, Jeroen; Bouwman, Wim; Habicht, Klaus; Tremsin, Anton; Strobl, Markus

    2016-06-15

    Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) in Time-of-Flight (ToF) mode has been shown to be a promising technique for measuring (very) small angle neutron scattering (SANS) signals and performing quantitative Dark-Field Imaging (DFI), i.e., SANS with 2D spatial resolution. However, the wavelength dependence of the modulation period in the ToF spin-echo mode has so far limited the useful modulation periods to those resolvable with the limited spatial resolution of the detectors available. Here we present our results of an approach to keep the period of the induced modulation constant for the wavelengths utilised in ToF. This is achieved by ramping the magnetic fields in the coils responsible for creating the spatially modulated beam in synchronisation with the neutron pulse, thus keeping the modulation period constant for all wavelengths. Such a setup enables the decoupling of the spatial detector resolution from the resolution of the modulation period by the use of slits or gratings in analogy to the approach in grating-based neutron DFI.

  2. Bilayer thickness in unilamellar phosphatidylcholine vesicles: small-angle neutron scattering using contrast variation

    NASA Astrophysics Data System (ADS)

    Kučerka, N.; Uhríková, D.; Teixeira, J.; Balgavý, P.

    2004-07-01

    The thickness of the lipid bilayer in extruded unilamellar vesicles prepared from synthetic 1,2-diacyl-sn-glycero-3-phosphorylcholines with monounsaturated acyl chains (diCn:1PC, n=14-22) was studied at 30°C in the small-angle neutron scattering (SANS) experiment. Several contrasts of the neutron scattering length density between the aqueous phase and phospholipid bilayer of vesicles were used. The experimental data were evaluated using the small-angle form of the Kratky-Porod approximation ln[I(q)q2] vs. q2 of the SANS intensity I(q) in the appropriate range of scattering vector values q to obtain the bilayer radius of gyration Rg and its extrapolated value at infinite scattering contrast Rginf. The bilayer thickness parameter evaluated from a linear approximation of dependence of gyration radius on the inverse contrast was then obtained without using any bilayer structure model. The dependence of the thickness parameter dg≅120.5Rginf on the number n of acyl chain carbons was found to be linear with a slope of 1.8+/-0.2Å per one acyl chain carbon. This slope can be used in bilayer-protein interaction studies.

  3. Clustering of water molecules in ultramicroporous carbon: In-situ small-angle neutron scattering

    SciTech Connect

    Bahadur, Jitendra; Contescu, Cristian I.; Rai, Durgesh K.; Gallego, Nidia C.; Melnichenko, Yuri B.

    2016-10-19

    The adsorption of water is central to most of the applications of microporous carbon as adsorbent material. We report early kinetics of water adsorption in the microporous carbon using in-situ small-angle neutron scattering. It is observed that adsorption of water occurs via cluster formation of molecules. Interestingly, the cluster size remains constant throughout the adsorption process whereas number density of clusters increases with time. The role of surface chemistry of microporous carbon on the early kinetics of adsorption process was also investigated. Lastly, the present study provides direct experimental evidence for cluster assisted adsorption of water molecules in microporous carbon (Do-Do model).

  4. Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

    SciTech Connect

    Worcester, D.L.; Katz, J.J.

    1994-12-31

    Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized.

  5. Study of structural irregularities of smectite clay systems by small-angle neutron scattering and adsorption

    NASA Astrophysics Data System (ADS)

    De Stefanis, A.; Tomlinson, A. A. G.; Steriotis, Th. A.; Charalambopoulou, G. Ch.; Keiderling, U.

    2007-04-01

    Small angle neutron scattering (SANS) and its contrast-matching variant are employed in order to determine structural properties (inter-pillar distances and mass/surface fractal dimensions of the clay layers and pillars) of a series of smectite natural clays (montmorillonite, beidellite, and bentonite) and their pillared and pillared/ion-exchanged analogues. Moreover, a comparative analysis with the adsorption data is carried out on the basis of a systematic study of the structural changes induced by a particular treatment or modification (e.g. pillaring) of the clay systems.

  6. Small angle X-ray and neutron scattering on cadmium sulfide nanoparticles in silicate glass

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Yu. V.; Rempel, A. A.; Meyer, M.; Pipich, V.; Gerth, S.; Magerl, A.

    2016-08-01

    Small angle X-ray and neutron scattering on Cd and S doped glass annealed at 600 °C shows after the first 12 h nucleation and growth of spherical CdS nanoparticles with a radius of up to 34±4 Å. After the nucleation is completed after 24 h, further growth in this amorphous environment is governed by oriented particle attachment mechanism as found for a liquid medium. Towards 48 h the particle shape has changed into spheroidal with short and long axis of 40±2 Å and 120±2 Å, respectively.

  7. Application of small angle neutron scattering on the analysis of Korean compact jaw bone

    NASA Astrophysics Data System (ADS)

    Choi, Yong; Shin, E. J.; Seong, B. S.; Paik, D. J.

    2012-10-01

    Small angle neutron scattering (SANS) was applied to analyze the nano-structure of normal and osteoporosis compact bones of Korean jaw-bones. The SANS profiles revealed the directional and regular distributions of plate-like bone crystals, lacuna rough surface and nano-sized canliculi in the compact bones. A smaller amount of bone crystals, lacuna and canliculi were present in the osteoporosis bone than in normal human bone. Microstructure observation by transmission electron microscopy and density measurement by bone densitometry supported the SANS evaluation.

  8. Small-Angle Neutron Scattering Measurements of Magnetic Cluster Sizes in Magnetic Recording Disks

    SciTech Connect

    Toney, Michael F

    2003-06-17

    We describe Small Angle Neutron Scattering measurements of the magnetic cluster size distributions for several longitudinal magnetic recording media. We find that the average magnetic cluster size is slightly larger than the average physical grain size, that there is a broad distribution of cluster sizes, and that the cluster size is inversely correlated to the media signal-to-noise ratio. These results show that intergranular magnetic coupling in these media is small and they provide empirical data for the cluster-size distribution that can be incorporated into models of magnetic recording.

  9. Small-angle neutron and dynamic light scattering study of gelatin coacervates

    NASA Astrophysics Data System (ADS)

    Mohanty, B.; Aswal, V. K.; Goyal, P. S.; Bohidar, H. B.

    2004-08-01

    The state of intermolecular aggregates and that of folded gelatin molecules could be characterized by dynamic laser light and small-angle neutron scattering experiments, which implied spontaneous segregation of particle sizes preceding coacervation, which is a liquid-liquid phase transition phenomenon. Dynamic light scattering (DLS) data analysis revealed two particle sizes until precipitation was reached. The smaller particles having a diameter of 50 nm (stable nanoparticles prepared by coacervation method) were detected in the supernatant, whereas the inter-molecular aggregates having a diameter of 400 nm gave rise to coacervation. Small-angle neutron scattering (SANS) experiments revealed that typical mesh size of the networks exist in polymer dense phase (coacervates) [1]. Analysis of the SANS structure factor showed the presence of two length scales associated with this system that were identified as the correlation length or mesh size, xi = 10.6 Å of the network and the other is the size of inhomogeneities = 21.4 Å. Observations were discussed based on the results obtained from SANS experiments performed in 5% (w/v) gelatin solution at 60oC (xi = 50 Å, zeta = 113 Å) and 5% (w/v) gel at 28oC (xi = 47 Å, zeta = 115 Å) in aqueous phase [2] indicating smaller length scales in coacervate as compared to sol and gel.

  10. Large-area proportional counter camera for the US National Small-Angle Neutron Scattering Facility

    SciTech Connect

    Abele, R.K.; Allin, G.W.; Clay, W.T.; Fowler, C.E.; Kopp, M.K.

    1980-01-01

    An engineering model of a multiwire position-sensitive proportional-counter (PSPC) was developed, tested, and installed at the US National Small-Angle Neutron Scattering Facility at ORNL. The PSPC is based on the RC-encoding and time-difference decoding method to measure the spatial coordinates of the interaction loci of individual scattered neutrons. The active area of the PSPC is 65 cm x 65 cm, and the active depth is 3.6 cm. The spatial uncertainty in both coordinates is approx. 1.0 cm (fwhm) for thermal neutrons; thus, a matrix of 64 x 64 picture elements is resolved. The count rate capability for randomly detected neutrons is 10/sup 4/ counts per second, with < 3% coincidence loss. The PSPC gas composition is 63% /sup 3/He, 32% Xe, and 5% CO/sub 2/ at an absolute pressure of approx. 3 x 10/sup 5/ Pa (3 atm). The detection efficiency is approx. 90% for the 0.475-nm (4.75-A) neutrons used in the scattering experiments.

  11. Grazing-incidence small-angle neutron scattering from structures below an interface

    PubMed Central

    Nouhi, Shirin; Hellsing, Maja S.; Kapaklis, Vassilios; Rennie, Adrian R.

    2017-01-01

    Changes of scattering are observed as the grazing angle of incidence of an incoming beam increases and probes different depths in samples. A model has been developed to describe the observed intensity in grazing-incidence small-angle neutron scattering (GISANS) experiments. This includes the significant effects of instrument resolution, the sample transmission, which depends on both absorption and scattering, and the sample structure. The calculations are tested with self-organized structures of two colloidal samples with different size particles that were measured on two different instruments. The model allows calculations for various instruments with defined resolution and can be used to design future improved experiments. The possibilities and limits of GISANS for different studies are discussed using the model calculations. PMID:28808432

  12. Grazing-incidence small-angle neutron scattering from structures below an interface.

    PubMed

    Nouhi, Shirin; Hellsing, Maja S; Kapaklis, Vassilios; Rennie, Adrian R

    2017-08-01

    Changes of scattering are observed as the grazing angle of incidence of an incoming beam increases and probes different depths in samples. A model has been developed to describe the observed intensity in grazing-incidence small-angle neutron scattering (GISANS) experiments. This includes the significant effects of instrument resolution, the sample transmission, which depends on both absorption and scattering, and the sample structure. The calculations are tested with self-organized structures of two colloidal samples with different size particles that were measured on two different instruments. The model allows calculations for various instruments with defined resolution and can be used to design future improved experiments. The possibilities and limits of GISANS for different studies are discussed using the model calculations.

  13. The 40m General Purpose Small-Angle Neutron Scattering Instrument at Oak Ridge National Laboratory

    SciTech Connect

    Wignall, George D; Bailey, Katherine M; Buchanan, Michelle V; Butler, Paul D; Heller, William T; Littrell, Ken; Lynn, Gary W; Melnichenko, Yuri B; Myles, Dean A A; Urban, Volker S

    2012-01-01

    A high-flux, 40m long small-angle neutron scattering (SANS) instrument has been constructed at Oak Ridge National Laboratory (ORNL). The facility utilizes a mechanical velocity selector, pinhole collimation and a high count-rate (> 105 Hz), large-area (1m2) two-dimensional position-sensitive detector. The incident wavelength ( ), resolution ( / ), incident collimation and sample-detector distance are independently variable under computer control. The detector can translate 45cm off axis to increase the overall Q-range (< 0.001 < Q = 4 -1sin < 1 -1), where 2 is the angle of scatter. The design and characteristics of this instrument are described along with examples of scattering data to illustrate the performance.

  14. Characterization of Nanocellulose Using Small-Angle Neutron, X-ray, and Dynamic Light Scattering Techniques.

    PubMed

    Mao, Yimin; Liu, Kai; Zhan, Chengbo; Geng, Lihong; Chu, Benjamin; Hsiao, Benjamin S

    2017-02-16

    Nanocellulose extracted from wood pulps using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and sulfuric acid hydrolysis methods was characterized by small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) techniques. The dimensions of this nanocellulose (TEMPO-oxidized cellulose nanofiber (TOCN) and sulfuric acid hydrolyzed cellulose nanocrystal (SACN)) revealed by the different scattering methods were compared with those characterized by transmission electron microscopy (TEM). The SANS and SAXS data were analyzed using a parallelepiped-based form factor. The width and thickness of the nanocellulose cross section were ∼8 and ∼2 nm for TOCN and ∼20 and ∼3 nm for SACN, respectively, where the fitting results from SANS and SAXS profiles were consistent with each other. DLS was carried out under both the VV mode with the polarizer and analyzer parallel to each other and the HV mode having them perpendicular to each other. Using rotational and translational diffusion coefficients obtained under the HV mode yielded a nanocellulose length qualitatively consistent with that observed by TEM, whereas the length derived by the translational diffusion coefficient under the VV mode appeared to be overestimated.

  15. Laser desorption mass spectrometry and small angle neutron scattering of heavy fossil materials

    SciTech Connect

    Hunt, J.E.; Winans, R.E.; Thiyagarajan, P.

    1997-09-01

    The determination of the structural building blocks and the molecular weight range of heavy hydrocarbon materials is of crucial importance in research on their reactivity and for their processing. The chemically and physically heterogenous nature of heavy hydrocarbon materials, such as coals, heavy petroleum fractions, and residues, dictates that their structure and reactivity patterns be complicated. The problem is further complicated by the fact that the molecular structure and molecular weight distribution of these materials is not dependent on a single molecule, but on a complex mixture of molecules which vary among coals and heavy petroleum samples. Laser Desorption mass spectrometry (LDMS) is emerging as a technique for molecular weight determination having found widespread use in biological polymer research, but is still a relatively new technique in the fossil fuel area. Small angle neutron scattering (SANS) provides information on the size and shape of heavy fossil materials. SANS offers the advantages of high penetration power even in thick cells at high temperatures and high contrast for hydrocarbon systems dispersed in deuterated solvents. LDMS coupled with time of flight has the advantages of high sensitivity and transmission and high mass range. We have used LDMS to examine various heavy fossil-derived materials including: long chain hydrocarbons, asphaltenes from petroleum vacuum resids, and coals. This paper describes the application of laser desorption and small angle neutron scattering techniques to the analysis of components in coals, petroleum resids and unsaturated polymers.

  16. Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering

    PubMed Central

    Gurnon, A. Kate; Godfrin, P. Douglas; Wagner, Norman J.; Eberle, Aaron P. R.; Butler, Paul; Porcar, Lionel

    2014-01-01

    A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions. PMID:24561395

  17. Measuring material microstructure under flow using 1-2 plane flow-small angle neutron scattering.

    PubMed

    Gurnon, A Kate; Godfrin, P Douglas; Wagner, Norman J; Eberle, Aaron P R; Butler, Paul; Porcar, Lionel

    2014-02-06

    A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions.

  18. Small-angle neutron scattering of nanocrystalline gadolinium and holmium with random paramagnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Döbrich, Frank; Bick, Jens-Peter; Birringer, Rainer; Wolff, Matthias; Kohlbrecher, Joachim; Michels, Andreas

    2015-02-01

    A neutron study of nanocrystalline terbium (Balaji G et al 2008 Phys. Rev. Lett. 100 227202) has shown that the randomly oriented anisotropy of the paramagnetic susceptibility tensor may lead to strongly correlated nanoscale spin disorder in the paramagnetic state which can be probed very effectively by magnetic small-angle neutron scattering (SANS). In principle, this scenario is also applicable to other rare-earth metals and the size of the effect is expected to scale with the strength of the anisotropy in the paramagnetic state. Here, we report SANS results (in the paramagnetic state) on nanocrystalline inert-gas condensed samples of Gd and Ho, which represent the cases of low and high anisotropy, respectively.

  19. Small Angle Neutron Scattering experiments on ``side-on fixed"" liquid crystal polyacrylates

    NASA Astrophysics Data System (ADS)

    Leroux, N.; Keller, P.; Achard, M. F.; Noirez, L.; Hardouin, F.

    1993-08-01

    Small Angle Neutron Scattering experiments were carried out on liquid crystalline “side-on fixed” polyacrylates : we observe that the polymer backbone adopts a prolate conformation in the nematic phase. Such anisotropy of the global backbone is larger for smaller spacer length. In every case we measure at low temperatures a large chain extension as previously described in polysiloxanes. Par diffusion des neutrons aux petits angles nous observons que la chaîne de polyacrylates “en haltère” adopte une conformation type prolate en phase nématique. Son anisotropie est d'autant plus grande que l'espaceur est plus court. Dans tous les cas, nous retrouvons à basse température la forte extension de la chaîne polymère qui fut d'abord révélée dans les polysiloxanes.

  20. Small-angle neutron scattering study of radiation-induced defects in synthetic quartz

    SciTech Connect

    Lebedev, V. M. Lebedev, V. T.; Orlov, S. P.; Pevzner, B. Z.; Tolstikhin, I. N.

    2006-12-15

    The supraatomic structure of single crystals of synthetic quartz was studied by thermal neutron small-angle scattering in the initial state (dislocation densities 54 and 570 cm{sup -2}) and after irradiation in the WWR-M reactor (Petersburg Nuclear Physics Institute) by fast neutrons with energies E{sub n} > 0.1 MeV at fluences F{sub n} = 0.2 x 10{sup 17} -5 x 10{sup 18} neutrons/cm{sup 2}. It is established that fast neutrons form point, linear, and volume defects in the lattice throughout the entire volume of a sample. Large-volume structures-amorphous-phase nuclei-reach sizes of {approx}100 nm in quartz, while occupying a small total volume of {approx}0.3% even at the maximum fluence 5 x 10{sup 18} neutrons/cm{sup 2}. The main fraction of the damaged volume (up to 5%) corresponds to point (with a radius of gyration of 1-2 nm) and linear defects, giving a comparable contribution ({approx}1-4%). The extended linear structures with a radius of 2 nm, even at a moderate fluence of 7.7 x 10{sup 17} neutrons/cm{sup 2}, have a significant total length per volume unit ({approx}10{sup 11} cm/cm{sup 3}) and can form a connected network with a cell {approx}30 nm in size in the sample. Foreign atoms and molecules can migrate through channels of this network.

  1. Small-angle neutron scattering and molecular dynamics structural study of gelling DNA nanostars

    NASA Astrophysics Data System (ADS)

    Fernandez-Castanon, J.; Bomboi, F.; Rovigatti, L.; Zanatta, M.; Paciaroni, A.; Comez, L.; Porcar, L.; Jafta, C. J.; Fadda, G. C.; Bellini, T.; Sciortino, F.

    2016-08-01

    DNA oligomers with properly designed sequences self-assemble into well defined constructs. Here, we exploit this methodology to produce bulk quantities of tetravalent DNA nanostars (each one composed of 196 nucleotides) and to explore the structural signatures of their aggregation process. We report small-angle neutron scattering experiments focused on the evaluation of both the form factor and the temperature evolution of the scattered intensity at a nanostar concentration where the system forms a tetravalent equilibrium gel. We also perform molecular dynamics simulations of one isolated tetramer to evaluate the form factor numerically, without resorting to any approximate shape. The numerical form factor is found to be in very good agreement with the experimental one. Simulations predict an essentially temperature-independent form factor, offering the possibility to extract the effective structure factor and its evolution during the equilibrium gelation.

  2. SEC-SANS: size exclusion chromatography combined in situ with small-angle neutron scattering1

    PubMed Central

    Jordan, Ashley; Jacques, Mark; Merrick, Catherine; Devos, Juliette; Forsyth, V. Trevor; Porcar, Lionel; Martel, Anne

    2016-01-01

    The first implementation and use of an in situ size exclusion chromatography (SEC) system on a small-angle neutron scattering instrument (SANS) is described. The possibility of deploying such a system for biological solution scattering at the Institut Laue–Langevin (ILL) has arisen from the fact that current day SANS instruments at ILL now allow datasets to be acquired using small sample volumes with exposure times that are often shorter than a minute. This capability is of particular importance for the study of unstable biological macromolecules where aggregation or denaturation issues are a major problem. The first use of SEC-SANS on ILL’s instrument D22 is described for a variety of proteins including one particularly aggregation-prone system. PMID:27980509

  3. Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study

    NASA Astrophysics Data System (ADS)

    Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

    2006-11-01

    Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q∼0.12 Å -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 Å. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.

  4. Small-Angle Neutron Scattering study of the NIST mAb reference material

    NASA Astrophysics Data System (ADS)

    Castellanos, Maria Monica; Liu, Yun; Krueger, Susan; Curtis, Joseph

    Monoclonal antibodies (mAbs) are of great interest to the biopharmaceutical industry because they can be engineered to target specific antigens. Due to their importance, the biomanufacturing initiative at NIST is developing an IgG1 mAb reference material `NIST mAb', which can be used by industry, academia, and regulatory authorities. As part of this collaborative effort, we aim at characterizing the reference material using neutron scattering techniques. We have studied the small-angle scattering profile of the NIST mAb in a histidine buffer at 0 and 150 mM NaCl. Using Monte Carlo simulations, we generate an ensemble of structures and calculate their theoretical scattering profile, which can be directly compared with experimental data. Moreover, we analyze the structure factor to understand the effect of solution conditions on the protein-protein interactions. Finally, we have measured the solution scattering of the NIST mAb, while simultaneously performing freeze/thaw cycles, in order to investigate if the solution structure was affected upon freezing. The results from neutron scattering not only support the development of the reference material, but also provide insights on its stability and guide efforts for its development under different formulations.

  5. A new approach to quantification of metamorphism using ultra-small and small angle neutron scattering.

    SciTech Connect

    Anovitz, Lawrence {Larry} M; Lynn, Gary W; Cole, David R

    2009-12-01

    In this paper we report the results of a study using small angle and ultra-small angle neutron scattering techniques (SANS and USANS) to examine the evolution of carbonates during contact metamorphism. Data were obtained from samples collected along two transects in the metamorphosed Hueco limestone at the Marble Canyon, Texas, contact aureole. These samples were collected from the igneous contact out to {approx}1700 m. Scattering curves obtained from these samples show mass fractal behavior at low scattering vectors, and surface fractal behavior at high scattering vectors. Significant changes are observed in the surface and mass fractal dimensions as well as the correlation lengths (pore and grain sizes), surface area to volume ratio and surface Gibbs Free energy as a function of distance, including regions of the aureole outside the range of classic metamorphic petrology. A change from mass-fractal to non-fractal behavior is observed at larger scales near the outer boundary of the aureole that implies significant reorganization of pore distributions early in the metamorphic history. Surface fractal results suggest significant smoothing of grain boundaries, coupled with changes in pore sizes. A section of the scattering curve with a slope less than -4 appears at low-Q in metamorphosed samples, which is not present in unmetamorphosed samples. A strong spike in the surface area to volume ratio is observed in rocks near the mapped metamorphic limit, which is associated with reaction of small amounts of organic material to graphite. It may also represent an increase in pore volume or permeability, suggesting that a high permeability zone forms at the boundary of the aureole and moves outwards as metamorphism progresses. Neutron scattering data also correlate well with transmission electron microscopic (TEM) observations, which show formation of micro- and nanopores and microfractures during metamorphism. The scattering data are, however, quantifiable for a bulk rock

  6. Small-angle neutron and X-ray scattering reveal conformational changes in rhodopsin activation

    NASA Astrophysics Data System (ADS)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Perera, Suchitrhanga M. C. D.; Chawla, Udeep; Struts, Andrey V.; Graziono, Vito; Pingali, Sai Venkatesh; Heller, William T.; Qian, Shuo; Brown, Michael F.; Chu, Xiang-Qiang

    2015-03-01

    Understanding G-protein-coupled receptor (GPCR) activation plays a crucial role in the development of novel improved molecular drugs. During photo-activation, the retinal chromophore of the visual GPCR rhodopsin isomerizes from 11-cis to all-trans conformation, yielding an equilibrium between inactive Meta-I and active Meta-II states. The principal goals of this work are to address whether the activation of rhodopsin leads to a single state or a conformational ensemble, and how protein organizational structure changes with detergent environment in solution. We use both small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques to answer the above questions. For the first time we observe the change in protein conformational ensemble upon photo-activation by SANS with contrast variation, which enables the separate study of the protein structure within the detergent assembly. In addition, SAXS study of protein structure within detergent assembly suggests that the detergent molecules form a belt of monolayer (micelle) around protein with different geometrical shapes to keep the protein in folded state.

  7. Nature of radiation defects in synthetic quartz according to the small-angle neutron scattering data

    SciTech Connect

    Lebedev, V. M. Lebedev, V. T.; Orlov, S. P.; Pevzner, B. Z.; Tolstikhin, I. N.

    2007-05-15

    The supraatomic structure of single crystals of synthetic quartz in the initial state with a dislocation density of 570 cm{sup -2} and after irradiation in the VVR-M reactor at the Petersburg Nuclear Physics Institute with fast neutrons having the energy E{sub n} > 1 MeV in the range of fluences F{sub n} = 7.7 x 10{sup 17} -2.1 x 10{sup 20} neutrons/cm{sup 2} has been studied by small-angle scattering of thermal neutrons. It is established that fast neutrons form point, linear, and volume lattice defects throughout the entire sample volume. Large-volume structures (nuclei of the amorphous phase) in quartz, reaching {approx}100 nm in size, occupy a small total volume ({approx}1.5%) even at the maximum fluence 2.1 x 10{sup 20} neutrons/cm{sup 2}. The majority of damage is related to the point defects with the radius of gyration of 1-2 nm and linear defects, which give comparable contributions up to several percent.

  8. A time dependent kinetic small angle neutron scattering study of a novel YFe phase.

    PubMed

    Simmons, L M; Bentley, P M; Al-Jawad, M; Kilcoyne, S H

    2013-06-26

    Crystallization of amorphous Y67Fe33 into the YFe2 C15 Laves phase via a novel 'YFe' intermediate phase has been observed through to completion using time-resolved small angle neutron scattering (SANS). The nucleation and growth kinetics of the phase transformations have been studied at annealing temperatures below the crystallization temperatures for both the 'YFe' phase and the YFe2 phase. The SANS results agree with previously reported neutron diffraction and SANS data. At the annealing temperatures of 360, 370 and 380 °C, changes in the scattering intensity I(Q) occur as a result of the contrast between the amorphous matrix and the nucleating and growing Y and 'YFe' phases. Critical scattering occurs during each of the isotherms, relating to the full crystallization of Y67Fe33, and extrapolation gives a crystallization temperature of 382 °C. Beyond critical scattering, isotherms at 435, 450, and 465 °C reveal the details of the continuing transformation of the 'YFe' intermediate phase into the YFe2 C15 Laves phase.

  9. Small-Angle Neutron Scattering by the Magnetic Microstructure of Nanocrystalline Ferromagnets Near Saturation

    PubMed Central

    Weissmüller, J.; McMichael, R. D.; Michels, A.; Shull, R. D.

    1999-01-01

    The paper presents a theoretical analysis of elastic magnetic small-angle neutron scattering (SANS) due to the nonuniform magnetic microstructure in nanocrystalline ferromagnets. The reaction of the magnetization to the magnetocrystalline and magnetoelastic anisotropy fields is derived using the theory of micromagnetics. In the limit where the scattering volume is a single magnetic domain, and the magnetization is nearly aligned with the direction of the magnetic field, closed form solutions are given for the differential scattering cross-section as a function of the scattering vector and of the magnetic field. These expressions involve an anisotropy field scattering function, that depends only on the Fourier components of the anisotropy field microstructure, not on the applied field, and a micromagnetic response function for SANS, that can be computed from tabulated values of the materials parameters saturation magnetization and exchange stiffness constant or spin wave stiffness constant. Based on these results, it is suggested that the anisotropy field scattering function SH can be extracted from experimental SANS data. A sum rule for SH suggests measurement of the volumetric mean square anisotropy field. When magnetocrystalline anisotropy is dominant, then a mean grain size or the grain size distribution may be determined by analysis of SH.

  10. Small Angle Neutron Scattering Study of Nano Sized Precipitates in Ferrous Alloys.

    PubMed

    Han, Young-Soo; Park, Duck-Gun; Kobayashi, Satoru

    2015-11-01

    Nano-sized precipitates in a Fe-1 wt% Cu alloy were studied by SANS (Small Angle Neutron Scattering). The SANS experiments were performed with the 40 m SANS instrument at HANARO. Due to the ferromagnetic nature of the ferrous alloys, a horizontal magnetic field of 1 Tesla was applied during the SANS experiment. The nano-sized Cu precipitates were quantitatively analyzed by SANS in the Fe-1 wt% Cu alloy. The size of the precipitates increased from 2 nm to 4 nm with increasing aging time from 20 min. to 1800 min. at 753 K. The measured A-ratio obtained from SANS data increased from 2.2 to 6.6 with increasing aging time. It is surmised that Cu clusters containing a large amount of Fe are initiated at the early stage of aging and the Fe content in the Cu precipitate decreases with increasing aging time and eventually an almost pure BCC Cu precipitate is formed.

  11. Study of (Cyclic Peptide)-Polymer Conjugate Assemblies by Small-Angle Neutron Scattering.

    PubMed

    Koh, Ming Liang; FitzGerald, Paul A; Warr, Gregory G; Jolliffe, Katrina A; Perrier, Sébastien

    2016-12-19

    We present a fundamental study into the self-assembly of (cyclic peptide)-polymer conjugates as a versatile supramolecular motif to engineer nanotubes with defined structure and dimensions, as characterised in solution using small-angle neutron scattering (SANS). This work demonstrates the ability of the grafted polymer to stabilise and/or promote the formation of unaggregated nanotubes by the direct comparison to the unconjugated cyclic peptide precursor. This ideal case permitted a further study into the growth mechanism of self-assembling cyclic peptides, allowing an estimation of the cooperativity. Furthermore, we show the dependency of the nanostructure on the polymer and peptide chemical functionality in solvent mixtures that vary in the ability to compete with the intermolecular associations between cyclic peptides and ability to solvate the polymer shell. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Small angle neutron scattering as fingerprinting of ancient potteries from Sicily (Southern Italy)

    SciTech Connect

    Barone, G.; Mazzoleni, P.; Crupi, V.; Majolino, D.; Venuti, V.; Teixeira, J.

    2009-09-01

    Small angle neutron scattering measurements have been carried out in order to investigate, in microdestructive way, the mesoscopic structure of a variety of potteries of relevance to cultural heritage coming from different Sicilian (Southern Italy) archeological sites belonging to the 'Strait of Messina' area and dated back to 7th-3rd century B.C. Data have been compared with the mesoscopic parameters extracted for two series of clayey sediments typical of the Strait of Messina area and fired under controlled conditions. The observed agreement between the features of reference and archeological samples allowed us to estimate the maximum firing temperature of the latter. Information on the pore sizes was obtained by the use of the concept of fractal surface, and compared with porosimetry results.

  13. Small-angle neutron scattering from polymer hydrogels with memory effect for medicine immobilization

    SciTech Connect

    Kulvelis, Yu. V. Lebedev, V. T.; Trunov, V. A.; Pavlyuchenko, V. N.; Ivanchev, S. S.; Primachenko, O. N.; Khaikin, S. Ya.

    2011-12-15

    Hydrogels synthesized based on cross-linked copolymers of 2-hydroxyethyl methacrylate and functional monomers (acrylic acid or dimethylaminoethyl methacrylate), having a memory effect with respect to target medicine (cefazolin), have been investigated by small-angle neutron scattering. The hydrogels are found to have a two-level structural organization: large (up to 100 nm) aggregates filled with network cells (4-7 nm in size). The structural differences in the anionic, cationic, and amphiphilic hydrogels and the relationship between their structure and the ability of hydrogels to absorb moisture are shown. A relationship between the memory effect during cefazolin immobilization and the internal structure of hydrogels, depending on their composition and type of functional groups, is established.

  14. Micelle structural studies on oil solubilization by a small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Putra, Edy Giri Rachman; Seong, Baek Seok; Ikram, Abarrul

    2009-02-01

    A small-angle neutron scattering (SANS) technique was applied to reveal the micelle structural changes. The micelle structural changes of 0.3 M sodium dodecyl sulfate (SDS) concentration by addition of various oil, i.e. n-hexane, n-octane, and n-decane up to 60% (v/v) have been investigated. It was found that the size, aggregation number and the structures of the micelles changed exhibiting that the effective charge on the micelle decreases with an addition of oil. There was a small increase in minor axis of micelle while the correlation peak shifted to a lower momentum transfer Q and then to higher Q by a further oil addition.

  15. Structure of phase-inversion membranes from small-angle neutron scattering data

    NASA Astrophysics Data System (ADS)

    Kul'velis, Yu. V.; Kononova, S. V.; Romashkova, K. A.; Lebedev, V. T.

    2014-01-01

    The structure of gradient-porous (asymmetric) membranes based on polyamide imide at different conditions of their formation has been investigated using small-angle neutron scattering. It has been shown that the membranes consist of rigid porous networks with well-defined interfaces between the polymer and the pores. It has been found that there are differences in the packings of structural elements of porous membranes-spherical pores with radii from 4 to 100 nm—depending on the membrane preformation time, drying regime, and the presence of fullerene C60 for modifying the mechanical and selective properties of membranes. The membranes also contain larger pores of micrometer sizes. Differences in the rates of saturation of membranes with water and their limiting swelling ratios are found, which can be explained by the structure of the dense layers of membranes (skin layer) and their different hydrophilities (depending on the fullerene content).

  16. Aggregates structure analysis of petroleum asphaltenes with small-angle neutron scattering.

    SciTech Connect

    Tanaka, R.; Hunt, J. E.; Winans, R. E.; Thiyagarajan, P.; Sato, S.; Takanohashi, T.; Idemitsu Kosan Co.; National Institute of Advanced Industrial Science and Technology

    2003-01-01

    The objective of this study is to examine changes in the structures of petroleum asphaltene aggregates in situ with small-angle neutron scattering (SANS). Asphaltenes were isolated from three different crude oils: Maya, Khafji, and Iranian Light. An aliquot of the 5 wt % asphaltene solution in deuterated Decalin, 1-methylnaphthalene, or quinoline was loaded in a special stainless steel cell for SANS measurements. SANS data measured at various temperatures from 25 to 350 {sup o}C showed various topological features different with asphaltene or solvent species. A fractal network was formed only with asphaltene of Maya in Decalin, and it remained even at 350 {sup o}C. In all of the solvents, asphaltenes aggregate in the form of a prolate ellipsoid with a high aspect ratio at 25 {sup o}C and got smaller with increasing temperature. That became a compact sphere with the size of around 25 {angstrom} in radius at 350 {sup o}C.

  17. Elucidating the Molecular Deformation Mechanism of Entangled Polymers in Fast Flow by Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Wang, Yangyang; Sanchez-Diaz, Luis; Cheng, Shiwang; Hong, Kunlun; Chen, Wei-Ren; Liu, Jianning; Lin, Panpan; Wang, Shi-Qing

    Understanding the viscoelastic properties of polymers is of fundamental and practical importance because of the vast and ever expanding demand of polymeric materials in daily life. Our current theoretical framework for describing the nonlinear flow behavior of entangled polymers is built upon the tube model pioneered by de Gennes, Doi, and Edwards. In this work, we critically examine the central hypothesis of the tube model for nonlinear rheology using small angle neutron scattering (SANS). While the tube model envisions a unique non-affine elastic deformation mechanism for entangled polymers, our SANS measurements show that the evolution of chain conformation of a well-entangled polystyrene melt closely follows the affine deformation mechanism in uniaxial extension, even when the Rouse Weissenberg number is much smaller than unity. This result provides a key clue for understanding the molecular deformation mechanism of entangled polymers in fast flow. Several implications from our analysis will be discussed in this talk.

  18. Clustering of water molecules in ultramicroporous carbon: In-situ small-angle neutron scattering

    DOE PAGES

    Bahadur, Jitendra; Contescu, Cristian I.; Rai, Durgesh K.; ...

    2016-10-19

    The adsorption of water is central to most of the applications of microporous carbon as adsorbent material. We report early kinetics of water adsorption in the microporous carbon using in-situ small-angle neutron scattering. It is observed that adsorption of water occurs via cluster formation of molecules. Interestingly, the cluster size remains constant throughout the adsorption process whereas number density of clusters increases with time. The role of surface chemistry of microporous carbon on the early kinetics of adsorption process was also investigated. Lastly, the present study provides direct experimental evidence for cluster assisted adsorption of water molecules in microporous carbonmore » (Do-Do model).« less

  19. Protein structure and interactions in the solid state studied by small-angle neutron scattering.

    PubMed

    Curtis, Joseph E; McAuley, Arnold; Nanda, Hirsh; Krueger, Susan

    2012-01-01

    Small-angle neutron scattering (SANS) is uniquely qualified to study the structure of proteins in liquid and solid phases that are relevant to food science and biotechnological applications. We have used SANS to study a model protein, lysozyme, in both the liquid and water ice phases to determine its gross-structure, interparticle interactions and other properties. These properties have been examined under a variety of solution conditions before, during, and after freezing. Results for lysozyme at concentrations of 50 mg mL(-1) and 100 mg mL(-1), with NaCl concentrations of 0.4 M and 0 M, respectively, both in the liquid and frozen states, are presented and implications for food science are discussed.

  20. Small angle neutron scattering (SANS and V-SANS) study of asphaltene aggregates in crude oil.

    PubMed

    Headen, Thomas F; Boek, Edo S; Stellbrink, Jörg; Scheven, Ulrich M

    2009-01-06

    We report small angle neutron scattering (SANS) experiments on two crude oils. Analysis of the high-Q SANS region has probed the asphaltene aggregates in the nanometer length scale. We find that the radius of gyration decreases with increasing temperature. We show that SANS measurements on crude oils give similar aggregate sizes to those found from SANS measurements of asphaltenes redispersed in deuterated toluene. The combined use of SANS and V-SANS on crude oil samples has allowed the determination of the radius of gyration of large scale asphaltene aggregates of approximately 0.45 microm. This has been achieved by the fitting of Beaucage functions over two size regimes. Analysis of the fitted Beaucage functions at very low-Q has shown that the large scale aggregates are not simply made by aggregation of all the smaller nanoaggregates. Instead, they are two different aggregates coexisting.

  1. Structure of nanocrystalline palladium and copper studied by small angle neutron scattering

    SciTech Connect

    Sanders, P.G.; Weertman, J.R.; Barker, J.G.

    1996-12-01

    The structure of nanocrystalline palladium and copper, made by inert gas condensation and compaction, was studied using small angle neutron scattering (SANS), optical microscopy, and scanning electron microscopy. The effects of annealing and warm compaction were also examined with these techniques. The SANS results were interpreted using a maximum entropy routine, combined with knowledge of the Archimedes density and hydrogen concentration determined by prompt gamma activation analysis (PGAA). Similar hydrogen concentrations were detected by SANS and PGAA. This hydrogen content, which was approximately 5 at.{percent} in samples compacted at room temperature, was reduced by both annealing and warm compaction. Defects in several size classes were observed, including missing grain pores ({approx_equal}1{endash}50 nm diameter) and defects of micrometer size. Warm compaction produced a lower number density of pores in nanocrystalline palladium, which led to increased density. The observed structure was correlated with Vickers microhardness and fracture surface morphology. {copyright} {ital 1996 Materials Research Society.}

  2. Small angle neutron scattering study to determine the structure of high strength hydrogels.

    NASA Astrophysics Data System (ADS)

    Tominaga, Taiki; Tirumala, Vijay R.; Lin, Eric K.; Wu, Wen-Li; Gong, Jian Ping; Furukawa, Hidemitsu; Osada, Yoshihito

    2006-03-01

    Hydrogels are swollen polymer networks containing more than 90% water. Most hydrogels, however, are mechanically too weak to be used as load bearing devices. Gong et al. have overcome this problem by synthesizing hydrogels with a double network (DN) structure. Modifying the polyelectrolyte network structure by polymerization of high molecular weight uncharged polymer in situ, resulted in orders of magnitude increase in their load bearing ability. Despite 90% water, these tough gels exhibit a fracture stress of 170 kg/cm^2, similar to that of articular cartilage found in the bone-joints of human body. In this work, we determined the structure of DN-gels using small angle neutron scattering. Structural origins for high toughness found in DN-gels were then examined by comparing the structure of DN-gels with that of pure polyelectrolyte network and polyacrylamide solution.

  3. Study of the enzyme ascorbate oxidase by small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Maritano, S.; Carsughi, F.; Fontana, M. P.; Marchesini, A.

    1996-09-01

    We report a study of the large scale structure of the "blue" copper enzyme ascorbate oxidase by small angle neutron scattering. The enzyme has been extracted from zucchini and studied in solutions of two different preparations. Contrast variation method was used by performing the measurements in water, heavy water and mixtures of H 2OD 2O. Our data show that, at least at the concentrations used here, the gyration radius of the enzyme is about 34 Å; with such a value our analysis is most consistent with a value of 70 KDa for the molecular weight of ascorbate oxidase in the conditions of our experiment. This is in contrast to the generally accepted value of 140 KDa, obtained by other techniques at high concentrations (e.g. greater than 2 mg ml -1). The possible origins of such a discrepancy are discussed.

  4. Recent applications of small-angle neutron scattering in strongly interacting soft condensed matter

    NASA Astrophysics Data System (ADS)

    Wignall, G. D.; Melnichenko, Y. B.

    2005-08-01

    Before the application of small-angle neutron scattering (SANS) to the study of polymer structure, chain conformation studies were limited to light and small-angle x-ray scattering techniques, usually conducted in dilute solution owing to the difficulties of separating the inter- and intrachain contributions to the structure. The unique role of neutron scattering in soft condensed matter arises from the difference in the coherent scattering length between deuterium (bD = 0.67 × 10-12 cm) and hydrogen (bH = -0.37 × 10-12 cm), which results in a marked difference in scattering power (contrast) between molecules synthesized from normal (hydrogeneous) and deuterated monomer units. Thus, deuterium labelling techniques may be used to 'stain' molecules and make them 'visible' in the condensed state and other crowded environments, such as concentrated solutions of overlapping chains. For over two decades, SANS has proved to be a powerful tool for studies of structure-property relationships in polymeric systems and has made it possible to extract unique information about their size, shape, conformational changes and molecular associations. These applications are now so numerous that an exhaustive review of the field is no longer practical, so the authors propose to focus on the use of SANS for studies of strongly interacting soft matter systems. This paper will therefore discuss basic theory and practical aspects of the technique and will attempt to explain the physics of scattering with the minimum of unnecessary detail and mathematical rigour. Examples will be given to demonstrate the power of SANS and to show how it has helped to unveil universal aspects of the behaviour of macromolecules in such apparently diverse systems as polymer solutions, blends, polyelectrolytes and supercritical mixtures. The aim of the authors is to aid potential users who have a general scientific background, but no specialist knowledge of scattering, to understand the potential of the

  5. Nonuniformity in natural rubber as revealed by small-angle neutron scattering, small-angle X-ray scattering, and atomic force microscopy.

    PubMed

    Karino, Takeshi; Ikeda, Yuko; Yasuda, Yoritaka; Kohjiya, Shinzo; Shibayama, Mitsuhiro

    2007-02-01

    The microscopic structures of natural rubber (NR) and deproteinized NR (DPNR) were investigated by means of small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM). They were compared to those of isoprene rubber (IR), which is a synthetic analogue of NR in terms of chemical structure without any non-rubber components like proteins. Comparisons of the structure and mechanical properties of NR, DPNR, and IR lead to the following conclusions. (i) The well-known facts, for example, the outstanding green strength of NR and strain-induced crystallization, are due not much to the presence of proteins but to other components such as the presence of phospholipids and/or the higher stereoregularity of NR. It also became clear the naturally residing proteins accelerate the upturn of stress at low strain. The protein phases work as cross-linking sites and reinforcing fillers in the rubbery matrix. (ii) The microscopic structures of NR were successfully reproduced by SANS intensity functions consisting of squared-Lorentz and Lorentz functions, indicating the presence of inhomogeneities in bulk and thermal concentration fluctuations in swollen state, respectively. On the other hand, IR rubbers were homogeneous in bulk. (iii) The inhomogeneities in NR are assigned to protein aggregates of the order of 200 A or larger. Although these aggregates are larger in size as well as in volume fraction than those of cross-link inhomogeneities introduced by cross-linking, they are removed by deproteinization. (iv) Swelling of both NR and IR networks introduces gel-like concentration fluctuations whose mesh size is of the order of 20 A.

  6. Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles

    PubMed Central

    Eicher, Barbara; Heberle, Frederick A.; Marquardt, Drew; Rechberger, Gerald N.; Katsaras, John

    2017-01-01

    Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effort but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ∼120 nm diameter palmitoyl­oleoyl phosphatidyl­choline (POPC) vesicles, compared to the inner leaflet. Analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K, i.e. above the melting transition temperature of the two lipids. PMID:28381971

  7. Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles

    DOE PAGES

    Eicher, Barbara; Heberle, Frederick A.; Marquardt, Drew T.; ...

    2017-02-28

    Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effortmore » but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ~120 nm diameter palmitoyloleoyl phosphatidylcholine (POPC) vesicles, compared to the inner leaflet. Here, analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K,i.e.above the melting transition temperature of the two lipids.« less

  8. Small-angle neutron scattering correlation functions of bulk magnetic materials

    PubMed Central

    Mettus, Denis; Michels, Andreas

    2015-01-01

    On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g. the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strength H p to the jump ΔM in the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratio H p/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel. PMID:26500464

  9. Investigation of the tripoli porous structure by small-angle neutron scattering

    SciTech Connect

    Avdeev, M. V.; Blagoveshchenskii, N. M.; Garamus, V. M.; Novikov, A. G. Puchkov, A. V.

    2011-12-15

    The characteristics of the tripoli porous structure have been investigated by small-angle neutron scattering (SANS). Tripoli is a finely porous sedimentary rock formed by small spherical opal particles. Its main component is aqueous silica SiO{sub 2} {center_dot} nH{sub 2}O (80-90%). Tripoli is widely used in practice as a working medium for sorption filters and in some other commercial and construction technologies. The shape of the experimental SANS curves indicates the presence of small and large pores in tripoli. The small-pore size was estimated to be {approx}100 Angstrom-Sign . The size of large pores turned out to be beyond the range of neutron wave vector transfers Q that are available for the instrument used; however, their size was indirectly estimated to be {approx}(2000-2500) Angstrom-Sign . The pores of both groups behave as surfacetype fractal scatterers with the fractal dimension D {approx} 2.2-2.6. The densities of pores of these two groups differ by approximately three orders of magnitude ({approx}10{sup 16} and {approx}10{sup 13} cm{sup -3} for small and large pores, respectively); the fraction of large pores amounts to 70-80% of the total pore volume. The found pore characteristics (their densities, sizes, and relative volumes) are in satisfactory agreement (when a comparison is possible) with the absorption data.

  10. Insight into asphaltene nanoaggregate structure inferred by small angle neutron and X-ray scattering.

    PubMed

    Eyssautier, Joëlle; Levitz, Pierre; Espinat, Didier; Jestin, Jacques; Gummel, Jérémie; Grillo, Isabelle; Barré, Loïc

    2011-06-02

    Complementary neutron and X-ray small angle scattering results give prominent information on the asphaltene nanostructure. Precise SANS and SAXS measurements on a large q-scale were performed on the same dilute asphaltene-toluene solution, and absolute intensity scaling was carried out. Direct comparison of neutron and X-ray spectra enables description of a fractal organization made from the aggregation of small entities of 16 kDa, exhibiting an internal fine structure. Neutron contrast variation experiments enhance the description of this nanoaggregate in terms of core-shell disk organization, giving insight into core and shell dimensions and chemical compositions. The nanoaggregates are best described by a disk of total radius 32 Å with 30% polydispersity and a height of 6.7 Å. Composition and density calculations show that the core is a dense and aromatic structure, contrary to the shell, which is highly aliphatic. These results show a good agreement with the general view of the Yen model (Yen, T. F.; et al. Anal. Chem.1961, 33, 1587-1594) and as for the modified Yen model (Mullins, O. C. Energy Fuels2010, 24, 2179-2207), provide characteristic dimensions of the asphaltene nanoaggregate in good solvent.

  11. Small angle neutron scattering studies of the structure of nucleosome cores at low ionic strength

    NASA Astrophysics Data System (ADS)

    Mita, Kazuei; Zama, Mitsuo; Ichimura, Sachiko; Niimura, Nobuo; Kaji, Keisuke; Hirai, Mitsuhiro; Ishikawa, Yoshikazu

    1983-05-01

    The structure of the nucleosome core particle at low ionic strenth (10-0.04 mM Na +) has been studied by small angle neutron scattering in various H 2O/D 2O mixtures. At 0.04 mM Na +,the radius of gyration obtained at 39% D 2O where scattering from the DNA dominates was 32 Å, and at 65% D 2O where scattering from the histones dominates, 40 Å. An abrupt increase in the radius of gyration from 35 to 40 Å was observed at about 1 mM ionic strength at 65% D 2O, with decreasing the ionic strength from 10 mM. No loss of the histone secondary structure was detected by circular dichroism over the range of the ionic strength examined. These results suggest that at low ionic strength (⪅1 mM) the histones are located outside of the nucleosome core particle accompanied by an alteration of the tertiary and/or quaternary structure of the histone octamer, with the DNA in a folded conformation.

  12. Estimation and modeling of coal pore accessibility using small angle neutron scattering

    SciTech Connect

    Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; Elsworth, Derek; Melnichenko, Yuri; He, Lilin; Wang, Yi

    2015-09-04

    Gas diffusion in coal is controlled by nano-structure of the pores. The interconnectivity of pores not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify pore accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical pore accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas pressure using deuterated methane (CD4) at low Q values for both coals. Pores smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the pore radius is larger than 40 nm, the pore accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of pores are accessible to CD4 for anthracite and 37% for sub-bituminous coal, where the pore radius is 16 nm. For these two coals, pore accessibility and pore radius follows a power-law relationship.

  13. Estimation and modeling of coal pore accessibility using small angle neutron scattering

    DOE PAGES

    Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; ...

    2015-09-04

    Gas diffusion in coal is controlled by nano-structure of the pores. The interconnectivity of pores not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify pore accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical pore accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas pressure using deuterated methane (CD4) at low Qmore » values for both coals. Pores smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the pore radius is larger than 40 nm, the pore accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of pores are accessible to CD4 for anthracite and 37% for sub-bituminous coal, where the pore radius is 16 nm. For these two coals, pore accessibility and pore radius follows a power-law relationship.« less

  14. Preliminary analysis of the distribution of water in human hair by small-angle neutron scattering.

    PubMed

    Kamath, Yash; Murthy, N Sanjeeva; Ramaprasad, Ram

    2014-01-01

    Diffusion and distribution of water in hair can reveal the internal structure of hair that determines the penetration of various products used to treat hair. The distribution of water into different morphological components in unmodified hair, cuticle-free hair, and hair saturated with oil at various levels of humidity was examined using small-angle neutron scattering (SANS) by substituting water with deuterium oxide (D(2)O). Infrared spectroscopy was used to follow hydrogen-deuterium exchange. Water present in hair gives basically two types of responses in SANS: (i) interference patterns, and (ii) central diffuse scattering (CDS) around the beam stop. The amount of water in the matrix between the intermediate filaments that gives rise to interference patterns remained essentially constant over the 50-98% humidity range without swelling this region of the fiber extensively. This observation suggests that a significant fraction of water in the hair, which contributes to the CDS, is likely located in a different morphological region of hair that is more like pores in a fibrous structure, which leads to significant additional swelling of the fiber. Comparison of the scattering of hair treated with oil shows that soybean oil, which diffuses less into hair, allows more water into hair than coconut oil. These preliminary results illustrate the utility of SANS for evaluating and understanding the diffusion of deuterated liquids into different morphological structures in hair.

  15. Small-angle neutron scattering study of organic-phase aggregation in the TALSPEAK process.

    PubMed

    Grimes, Travis S; Jensen, Mark P; Debeer-Schmidt, Lisa; Littrell, Ken; Nash, Kenneth L

    2012-11-26

    The Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes (TALSPEAK) process is a solvent extraction based method for separating trivalent lanthanides (Ln(3+)) from trivalent actinide cations in used nuclear fuel reprocessing. In conventional TALSPEAK, the extractant solution is di(2-ethylhexyl)phosphoric acid (HDEHP) in 1,4-diisopropylbenzene (DIPB). The aqueous medium is diethylenetriamine-N,N,N',N″,N″-pentaacetic acid (DTPA) in a concentrated lactic acid (HL) buffer. Lanthanides are extracted by HDEHP/DIPB, while the actinides remain in the aqueous phase as DTPA complexes. Lactic acid is extracted both independently of the lanthanides and as Ln/HL/HDEHP mixed complex(es). Previous results indicate that lanthanides are extracted both as the mixed complex and as a binary Ln(DEHP·HDEHP)(3) species. Small-angle neutron scattering (SANS) has been applied to study the self-organization properties of solute molecules in xylene solutions containing HDEHP, HL, selected lanthanide ions, and water. The scattering results demonstrate that the dominant HDEHP species is the hydrogen bonded dimer, (HDEHP)(2). Absent lanthanides, lactic acid is extracted as the 1:3 complex (HL·(HDEHP)(3)). Scattering in samples containing up to 0.005 M lanthanides (prepared by extracting lanthanides from aqueous media containing 1.0 M buffered lactic acid) indicates that the dominant metal complex is Ln(DEHP·HDEHP)(3). At 0.013 M extracted lanthanide, the scattering results indicate lower Ln:DEHP stoichiometry and larger scattering particles. At higher metal concentrations, the SANS results indicate large aggregates, the largest aggregates achieving a size equivalent to 20 HDEHP monomers as the primary scattering entity. Analysis of particle shapes indicates best fits with a uniform oblate spheroid particle. These results are discussed in connection with the results of a number of complementary observations that have been made on this system.

  16. Small-angle Neutron Scattering and Contrast Variation: A Powerful Combination for Studying Biological Structures

    SciTech Connect

    Heller, William T

    2010-01-01

    The use of small-angle scattering (SAS) in the biological sciences continues to increase, driven as much by the need to study increasingly complex systems that are often resistant to crystallization or are too large for NMR as by the availability of user facilities and advancements in the modelling of biological structures from SAS data. SAS, whether with neutrons (SANS) or X-rays (SAXS), is a structural probe of length scales ranging from 10 to 10,000 {angstrom}. When applied to biological complexes in dilute solution, it provides size and shape information that can be used to produce structural models that can provide insight into function. SANS enables the use of contrast-variation methods through the unique interaction of neutrons with hydrogen and its isotope deuterium. SANS with contrast variation enables the visualization of components within multisubunit complexes, making it a powerful tool for probing protein-protein and protein-nucleic acid complexes, as well as the interaction of proteins with lipids and detergents.

  17. Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

    2015-03-01

    Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

  18. Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.

    SciTech Connect

    McCray, John; Navarre-Sitchler, Alexis; Mouzakis, Katherine; Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot

    2010-11-01

    Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of

  19. Characterization of polymer adsorption onto drug nanoparticles using depletion measurements and small-angle neutron scattering.

    PubMed

    Goodwin, Daniel J; Sepassi, Shadi; King, Stephen M; Holland, Simon J; Martini, Luigi G; Lawrence, M Jayne

    2013-11-04

    Production of polymer and/or surfactant-coated crystalline nanoparticles of water-insoluble drugs (nanosuspensions) using wet bead milling is an important formulation approach to improve the bioavailability of said compounds. Despite the fact that there are a number of nanosuspensions on the market, there is still a deficiency in the characterization of these nanoparticles where further understanding may lead to the rational selection of polymer/surfactant. To this end small-angle neutron scattering (SANS) measurements were performed on drug nanoparticles milled in the presence of a range of polymers of varying molecular weight. Isotopic substitution of the aqueous solvent to match the scattering length density of the drug nanoparticles (i.e., the technique of contrast matching) meant that neutron scattering resulted only from the adsorbed polymer layer. The layer thickness and amount of hydroxypropylcellulose adsorbed on nabumetone nanoparticles derived from fitting the SANS data to both model-independent and model dependent volume fraction profiles were insensitive to polymer molecular weight over the range Mv = 47-112 kg/mol, indicating that the adsorbed layer is relatively flat but with tails extending up to approximately 23 nm. The constancy of the absorbed amount is in agreement with the adsorption isotherm determined by measuring polymer depletion from solution in the presence of the nanoparticles. Insensitivity to polymer molecular weight was similarly determined using SANS measurements of nabumetone or halofantrine nanoparticles stabilized with hydroxypropylmethylcellulose or poly(vinylpyrrolidone). Additionally SANS studies revealed the amount adsorbed, and the thickness of the polymer layer was dependent on both the nature of the polymer and drug particle surface. The insensitivity of the adsorbed polymer layer to polymer molecular weight has important implications for the production of nanoparticles, suggesting that lower molecular weight polymers

  20. Miscibility Study of PCBM/P3EHT Organic Photovoltaics via Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Yin, Wen; McCulloch, Bryan; Segalman, Rachel; Dadmun, Mark

    2011-03-01

    Organic photovoltaics (OPV) attracted considerable interest as lightweight, inexpensive, and easily processable replacement of inorganic photovoltaics. Current results indicate that the morphology of these photovoltaic materials is essential to their solar energy conversion efficiency but a detailed and fundamental understanding is absent. In this paper, the miscibility and structure of P3EHT/PCBM composites with varying PCBM loading level are investigated via small angle neutron scattering (SANS). With P3EHT having a melting temperature below 100°C, SANS experiments of the blends are conducted above the melting point to unequivocally determine the miscibility of PCBM and P3EHT without the added complexity of polymer crystals. Our SANS results show that blends with 20 and 50 wt% PCBM exhibit dramatically larger scattering at low-Q regime relative to 10 and 15wt% PCBM samples. This result implies that the miscibility limit of PCBM and P3EHT lies between 15:85 and 20:80. Further analysis is underway to correlate these results to OPV efficiency.

  1. Using Small Angle Neutron Scattering on Glucose Oxidase immobilized on Single Layer Graphene

    NASA Astrophysics Data System (ADS)

    Rai, Durgesh; Gurusaran, M.; Qian, S.; Weiss, K.; Urban, V.; Li, P.; Ma, L.; Ajayan, P.; Narayanan, T.; Sekar, K.; Viswanathan, S.; Renugopalakrishanan, V.

    2015-03-01

    Reliable blood glucose monitoring using biosensors is valuable for health evaluations and medication in wake of chronic diabetic issues accompanying deviations from evolutionary human lifestyle. Glucose oxidase (GOx) is an ideal enzyme because of its specificity and the ability to electrochemically transduce from the enzymatic reaction. We use graphene-based electrode with GOx sensor matrix so that the emitted electrons from sensor matrix can flow across graphene nearly without scattering; crucial for constructing ultrasensitive-sensors. Thereafter, establishing a structure-property based relationships to tune the sensor topology with electrochemically output forms the main focus of the device development process. We have developed a methodology to obtain low-resolution hierarchical models of the aggregate matrix using Small Angle Neutron Scattering (SANS) technique. A Unified Fit model is used in tandem with GNOM, DAMMIN and DAMAVER to construct low-resolution models for GOx matrices. A detailed explanation of a general methodology for obtaining quantitative details aggregate structures along with qualitative models will be presented.

  2. New Insights into Pore Characteristics and Hydrocarbon Generation of Shale Using Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Ding, M.; Hartl, M.; Wang, Y.; Hjelm, R.

    2014-12-01

    Pore size, distribution, connectivity, and shape as well as hydrocarbon saturation and composition reflect the history of hydrocarbon maturation and migration. However, characterization of the underlying factors and processes controlling hydrocarbons behavior in tight rocks is extremely limited, especially lacking of direct experimental observations. We have studied the pore characteristics of marine and lacustrine shale from the Erdos basin, China during laboratory pyrolysis using small-angle neutron scattering (SANS). Our SANS results show that scattering intensity of smaller pores (< 20 nm)/larger Q values of shale samples increase systematically as temperature increase during pyrolysis from 250 oC to 600oC (Fig.1a). These results in combination with hydrocarbon fractions measurements during the same process (Fig. 1b) provide a quantitative relation between pore characteristics and hydrocarbons generation. Our results indicate that hydrocarbon expulsion primarily causes the observed changes in smaller pores. They also demonstrate that due to its sensitivity to hydrogen, SANS locates all pores whether the pore is filled or not with hydrocarbons. Thus, SANS is particularly suited for probing hydrocarbon behavior in tight shale reservoirs and the factors that impact their pore dynamics for the petroleum industry.

  3. Small angle neutron scattering study of fatigue induced grain boundary cavities

    SciTech Connect

    Page, R.; Roth, M.; Weertman, J.R.

    1982-07-01

    Small angle neutron scattering (SANS) has been used to study grain boundary cavitation in high purity copper fatigued at elevated temperatures. SANS is an extremely sensitive method for observing cavities. Void volume fractions of less than 10/sup -6/ can be detected. Analysis of scattering data yields values for the total void volume per unit volume and the total number of voids in a fatigued sample. The size distribution of the voids also can be calculated. From a series of specimens, each fatigued under identical conditions but for varying lengths of time, it is possible to obtain the void nucleation rate and the rate of growth of the total void volume and of the individual voids. Extrapolation of curves of void volume fraction vs time of fatigue to zero time shows that cavitation begins upon commencement of fatiguing without any measurable incubation time. Void nucleation is continuous throughout fatigue Calculated values of the individual void growth rate agree very well, as regards time dependence, temperature dependence, and even absolute value, with growth rates derived from a theory of fatigueinduced cavitation based on transient effects in vacancy diffusion.

  4. Solution Properties of 1,3-Cyclohexadiene Polymers by Small Angle Neutron and Light Scattering

    SciTech Connect

    Yun, Seok I; Melnichenko, Yuri B; Wignall, George D; Hong, Kunlun; Mays, Jimmy; Britt, Phillip F; Terao, Ken; Nakamura, Yo

    2006-01-01

    1,3-Cyclohexdiene polymers (PCHD) and their derivatives are of interest due to the six-member rings in the main chain, which are expected to impart higher mechanical strength and better thermal and chemical stability, as compared to common vinyl polymers. For example, hydrogenated PCHD has the highest glass transition temperature (T{sub g} {approx} 231 C) of all hydrocarbon polymers, and it also shows good heat, weather, impact, abrasion, and chemical resistance as well as low water absorption. In addition, PCHD has unique photochemical properties, such as excellent transparency, due to the isolated double bonds in the main chain. Also, block copolymers containing PCHD show unusual phase separation behavior. For example, a styrene/1,3-CHD block copolymer (PS-b-PCHD) with 50 vol % CHD (1,4/1,2 {approx} 95/5) exhibits a core-shell or hollow cylinder morphology, while a typical styrene/acyclic diene (isoprene or butadiene) block copolymer with similar composition exhibits a lamellar structure. Such phase behavior and many other properties strongly depend on the conformation of the polymer in solution or bulk. However, almost no data have been reported on the conformation of PCHD, probably because of the lack of well-defined and well-characterized samples. Here we report solution properties of PCHD in tetrahydrofuran (THF) and chloroform by multiangle laser light scattering, viscometry, and small-angle neutron scattering (SANS).

  5. Structural characterization of a polymer substituted fullerene (flagellene) by small angle neutron scattering

    SciTech Connect

    Affholter, K.A.; Bunick, G.J.; Wignall, G.D.; Desimone, J.M.; Hunt, M.O. Jr.; Menceloglu, Y.Z.; Samulski, E.T.

    1994-12-31

    Small-angle neutron scattering (SANS) can structurally characterize fullerenes in solvents with strong SANS contrast (e.g. CS{sub 2}). Deuterated solvents (e.g. toluene-d{sub 8}) have a high scattering length density (SLD), which is close to that of C{sub 60} and C{sub 70} moieties. Hence, there is virtually no SANS contrast with the solvent and these particles are practically ``invisible`` in such media. On the other hand, the negative scattering length of hydrogen means that the SLD of H{sup 1}-containing materials is much lower, so they have strong contrast with toluene-d{sub 8}. Thus, SANS makes it possible to study the size and shapes of modified buckyballs such as the polymer-substituted fullerenes, or flagellenes. These consist of C{sub 60} cores to which 1-4 polystryene chains (with a molecular weight, MW {approx_equal} 2000) are attached. The extrapolated cross section at zero angle of scatter [d{Sigma}/d{Omega}(0)] is a function of the number of pendant chains, so SANS can be used to assess the number of ``arms`` which are covalently attached to the fullerene ``sphere.`` Close agreement ({plus_minus}4%) between measured and calculated values of d{Sigma}/d{Omega}(0) along with independent estimates of the radius of gyration (R{sub g}) and second virial coefficient (A{sub 2}) for a calibration linear polystyrene sample serves as a cross check on the validity of this methodology.

  6. Membrane Structure Studies by Means of Small-Angle Neutron Scattering (SANS)

    SciTech Connect

    Knott, R. B.

    2008-03-17

    summary of membrane structure will be followed by an outline of the neutron scattering techniques used to understand membrane structure and dynamics. The emphasis will be on the small angle neutron scattering technique since there is a very powerful instrument at Serpong, however brief mention of other techniques will be included to demonstrate how a multidisciplinary approach is usually required.

  7. Small angle neutron scattering for the structural study of intrinsically disordered proteins in solution: a practical guide.

    PubMed

    Gabel, Frank

    2012-01-01

    Small angle neutron scattering (SANS) allows studying bio-macromolecular structures and interactions in solution. It is particularly well-suited to study structural properties of intrinsically disordered proteins (IDPs) over a wide range of length-scales ranging from global aspects (radii of gyration and molecular weight) down to short-distance properties (e.g., cross-sectional analysis). In this book chapter, we provide a practical guide on how to carry out SANS experiments on IDPs and discuss the complementary aspects and strengths of SANS with respect to small angle X-ray scattering (SAXS).

  8. Search for small-angle neutron scattering in MnO at 1700K

    SciTech Connect

    Routbort, J.L.; Epperson, J.E.; Klippert, T.E.; Goretta, K.C.

    1986-01-01

    A preliminary small-angle scattering (SANS) experiment has been performed on MnO single crystal at the Intense Pulsed Neutron Source. The experiment was preformed at 1700/sup 0/K at oxygen partial pressures of 2.2 x 10/sup -4/, 1 x 10/sup 2/, and 2 x 10/sup 2/ Pa, which resulted in deviations from stoichiometry of about 0.0015, 0.082, and 0.127. No statistically significant change in SANS was observed at this temperature with the pressure changes. Neither was any significant change observed in the wavelength-dependent sample transmission, also measured in-situ as a function of pressure. Therefore, either clustering of cation vacancies is negligible in MnO for these conditions, or the clusters are smaller than about 5 A. Of proposed cluster configurations, only the existence of the smallest (4:1, 6:2, or possible 8:3) appears to be consistent with these results.

  9. Microstructure of 3D-Printed Polymer Composites Investigated by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Kang, Tae Hui; Compton, Brett G.; Heller, William T.; Urban, Voker S.; Duty, Chad E.; Do, Changwoo

    Polymer composites printed from the large scale printer at Manufacturing Demonstration Facility at Oak Ridge National Laboratory have been investigated by small-angle neutron scattering (SANS). For the Acrylonitrile Butadiene Styrene (ABS)/Carbon Fiber (CF) composites, the microstructure of polymer domains and the alignment of CF have been characterized across the layer from the printed piece. CF shows strong anisotropic alignment along the printing direction due to the flow of polymer melt at the nozzle. Order parameter of the anisotropy which ranges from -0.11 to -0.06 exhibits strong correlation with the position within the layer: stronger alignment near the layer interface. It is also confirmed that the existence of CF reduces the polymer domain correlation length significantly and reinforces the mechanical strength of the polymer composites. For the Epoxy/nano-clay platelet composites, the effect of processing condition, nozzle size, and the addition of the another filler, Silicon Carbide (SC), have been investigated by SANS. Nano-clay platelet shows strong anisotropic alignment along the printing direction as well. Order parameter of the anisotropy varies according to nozzle size and presence of the SC, and difference disappears at high Q region. Scientific User Facilities Division and Materials Sciences and Energy Division, Office of Basic Energy Sciences, U.S. Department of Energy.

  10. Investigation of the interaction of dimethyl sulfoxide with lipid membranes by small-angle neutron scattering

    SciTech Connect

    Gorshkova, J. E. Gordeliy, V. I.

    2007-05-15

    The influence of dimethyl sulfoxide (CH{sub 3}){sub 2}SO (DMSO) on the structure of membranes of 1,2-dimiristoyl-sn-glycero-3-phosphatidylcholine (DMPC) in an excess of a water-DMSO solvent is investigated over a wide range of DMSO molar concentrations 0.0 {<=} X{sub DMSO} {<=} 1.0 at temperatures T = 12.5 and 55 deg. C. The dependences of the repeat distance d of multilamellar membranes and the thickness d{sub b} of single vesicles on the molar concentration X{sub DMSO} in the L{sub {beta}}{sub '} gel and L{sub {alpha}} liquid-crystalline phases are determined by small-angle neutron scattering. The intermembrane distance d{sub s} is determined from the repeat distance d and the membrane thickness d{sub b}. It is shown that an increase in the molar concentration X{sub DMSO} leads to a considerable decrease in the intermembrane distance and that, at X{sub DMSO} = 0.4, the neighboring membranes are virtually in steric contact with each other. The use of the deuterated phospholipid (DMSO-D6) and the contrast variation method makes it possible, for the first time, to determine the number of DMSO molecules strongly bound to the membrane.

  11. Ensemble Activation of G-Protein -Coupled Receptors Revealed by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Chu, Xiang-Qiang; Perera, Suchithranga; Shrestha, Utsab; Chawla, Udeep; Struts, Andrey; Qian, Shuo; Brown, Michael

    2014-03-01

    Rhodopsin is a G-protein -coupled receptor (GPCR) involved in visual light perception and occurs naturally in a membrane lipid environment. Rhodopsin photoactivation yields cis-trans isomerization of retinal giving equilibrium between inactive Meta-I and active Meta-II states. Does photoactivation lead to a single Meta-II conformation, or do substates exist as described by an ensemble-activation mechanism (EAM)? We use small-angle neutron scattering (SANS) to investigate conformational changes in rhodopsin-detergent and rhodopsin-lipid complexes upon photoactivation. Meta-I state is stabilized in CHAPS-solubilized rhodopsin, while Meta-II is trapped in DDM-solubilized rhodopsin. SANS data are acquired from 80% D2O solutions and at contrast-matching points for both DDM and CHAPS samples. Our experiments demonstrate that for detergent-solubilized rhodopsin, SANS with contrast variation can detect structural differences between the rhodopsin dark-state, Meta-I, Meta-II, and ligand-free opsin states. Dark-state rhodopsin has more conformational flexibility in DDM micelles compared to CHAPS, which is consistent with an ensemble of activated Meta-II states. Furthermore, time-resolved SANS enables study of the time-dependent structural transitions between Meta-I and Meta-II, which is crucial to understanding the ensemble-based activation.

  12. Small-Angle Neutron Scattering and Spontaneous Formation of Unilamellar Vesicles: Potential Vehicles for Drug Delivery

    NASA Astrophysics Data System (ADS)

    Katsaras, John

    2004-03-01

    Unilamellar vesicles (ULVs) are single-bilayer shells with radii commonly between 10 and 100 nm, and are widely used as model membranes, drug delivery systems, microreactors and substrates for a variety of enzymes and proteins. A common method of making ULVs is the extrusion of multilamellar vesicles (MLVs) through synthetic membranes of known pore size. These extruded ULVs are invariably unstable and in due time, revert back to MLVs. Over the years there have been reports of the spontaneous formation of stable ULVs in surfactant, lipid, and lipid/detergent mixtures. These ULVs have sometimes been shown to be monodisperse and their radii were found, almost without exception, to vary with concentration. We have carried-out small-angle neutron scattering (SANS) experiments on a biomimetic system composed of the phospholipids dimyristoyl and dihexanoyl phosphorylcholine (DMPC and DHPC, respectively). Doping DMPC/DHPC multilamellar vesicles with either the negatively charged lipid dimyristoyl phosphorylglycerol (DMPG, net charge -1) or the divalent cation, calcium (Ca2+) leads to the spontaneous formation of monodisperse unilamellar vesicles whose radii are concentration independent, in contrast to previous experimental observations.

  13. The kinetics of water sorption in Nafion membranes: a small-angle neutron scattering study.

    PubMed

    Gebel, Gérard; Lyonnard, Sandrine; Mendil-Jakani, Hakima; Morin, Arnaud

    2011-06-15

    The optimization of the water management in proton exchange membrane fuel cells is a major issue for the large-scale development of this technology. In addition to the operating conditions, the membrane water sorption and transport processes obviously control the water management. The main objective of this work is to provide new experimental evidence based on the use of the small-angle neutron scattering (SANS) technique in order to allow a better understanding of water sorption processes. SANS spectra were recorded for membranes equilibrated with either water vapor or liquid. Sorption kinetics data were determined and the SANS spectra were analyzed using the method developed for extracting water concentration profiles across the membrane in operating fuel cells. The water concentration profiles across the membrane are completely flat, which indicates that the water diffusion within the membrane is not the limiting process. This result provides new insight into the numerous data published on these properties. For the first time, the swelling kinetics of a Nafion membrane immersed in liquid water is studied and a complete swelling is obtained in less than 1 min.

  14. Small-angle neutron-scattering study of nanophase zirconia in a reverse micelle synthesis.

    SciTech Connect

    Lager, G. A.; Li, X.; Loong, C.-K.; Miranda, R.; Thiyagarajan, P.

    1999-07-02

    Nanophase zirconia particles are synthesized by mixing two reverse micelle solutions containing the precursor salt ZrOCl{sub 2} and the base NH{sub 4}OH. The primary reverse micelle solution consists of AOT, toluene and water. The reverse micelle structure of four solutions as a function of w (the molar ratio of [water]/[AOT]) is characterized by small-angle neutron scattering at room temperature. With the addition of ZrOCl{sub 2} and NH{sub 4}OH into the water pools, the reverse micelle sizes decrease as compared to those in the D{sub 2}O/AOT/C{sub 6}D{sub 5}CD{sub 3} primary system. The mixed microemulsions contain reverse micelle sizes that fail between the values of the pre-mixed solutions. All the reverse micelles exhibit uniform size and spherical shape. The effect of concentration of inorganic salt precursor in the water pools on the reverse micelle structure is also studied.

  15. Small-angle neutron scattering reveals a pH-dependent conformational change in cellobiohydrolase I

    SciTech Connect

    Pingali, Sai Venkatesh; O'Neill, Hugh Michael; McGaughey, Joseph; Urban, Volker S; Myles, Dean A A; Petridis, Loukas; Smith, Jeremy C; Evans, Barbara R; Heller, William T

    2011-01-01

    Cellobiohydrolase I (Cel7A) of the fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) hydrolyzes crystalline cellulose to soluble sugars, making it of key interest for producing fermentable sugars from biomass for biofuel production. The activity of the enzyme is pH-dependent, with its highest activity occurring at pH 4-5. To probe the response of the solution structure of Cel7A to changes in pH, we measured small angle neutron scattering of it in a series of solutions having pH values of 7.0, 6.0, 5.3, and 4.2. As the pH decreases from 7.0 to 5.3, the enzyme structure remains well defined, possessing a spatial differentiation between the cellulose binding domain and the catalytic core that only changes subtly. At pH 4.2, the solution conformation of the enzyme changes to a structure that is intermediate between a properly folded enzyme and a denatured, unfolded state, yet the secondary structure of the enzyme is essentially unaltered. The results indicate that at the pH of optimal activity, the catalytic core of the enzyme adopts a structure in which the compact packing typical of a fully folded polypeptide chain is disrupted and suggest that the increased range of structures afforded by this disordered state plays an important role in the increased activity of Cel7A through conformational selection.

  16. Small Angle Neutron Scattering Reveals pH-dependent Conformational Changes in Trichoderma reesei Cellobiohydrolase I

    PubMed Central

    Pingali, Sai Venkatesh; O'Neill, Hugh M.; McGaughey, Joseph; Urban, Volker S.; Rempe, Caroline S.; Petridis, Loukas; Smith, Jeremy C.; Evans, Barbara R.; Heller, William T.

    2011-01-01

    Cellobiohydrolase I (Cel7A) of the fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) hydrolyzes crystalline cellulose to soluble sugars, making it of key interest for producing fermentable sugars from biomass for biofuel production. The activity of the enzyme is pH-dependent, with its highest activity occurring at pH 4–5. To probe the response of the solution structure of Cel7A to changes in pH, we measured small angle neutron scattering of it in a series of solutions having pH values of 7.0, 6.0, 5.3, and 4.2. As the pH decreases from 7.0 to 5.3, the enzyme structure remains well defined, possessing a spatial differentiation between the cellulose binding domain and the catalytic core that only changes subtly. At pH 4.2, the solution conformation of the enzyme changes to a structure that is intermediate between a properly folded enzyme and a denatured, unfolded state, yet the secondary structure of the enzyme is essentially unaltered. The results indicate that at the pH of optimal activity, the catalytic core of the enzyme adopts a structure in which the compact packing typical of a fully folded polypeptide chain is disrupted and suggest that the increased range of structures afforded by this disordered state plays an important role in the increased activity of Cel7A through conformational selection. PMID:21784865

  17. Comparative analysis of the nucleosome structure of cell nuclei by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Isaev-Ivanov, V. V.; Lebedev, D. V.; Lauter, H.; Pantina, R. A.; Kuklin, A. I.; Islamov, A. Kh.; Filatov, M. V.

    2010-05-01

    The nucleosome structure in native nuclei of normal (chicken erythrocyte and rat leukocyte nuclei) and anomalously proliferating (the human cervical adenocarcinoma cell line HeLa and the Chinese hamster fibroblast cell line A238) cells has been investigated using small-angle neutron scattering. The experimental results obtained allow one to make the inference that the parameters of the nucleosome structure for the chicken erythrocyte and rat leukocyte nuclei (on average over the nucleus) are close to the universally accepted values and that the distance distribution function is bimodal. The bimodality of the distance distribution function reflects a narrow distribution of distances between nucleosomes (on average over the nucleus) at the fibril level of the chromatin organization. The histone core of the nucleosome structure in the nuclei of the HeLa and A238 cells (on average over the nucleus) is considerably less compact than that in the chicken erythrocyte and rat leukocyte nuclei, and the distance distribution function does not exhibit indications of the bimodality.

  18. Modeling and small-angle neutron scattering spectra of chromatin supernucleosomal structures at genome scale

    NASA Astrophysics Data System (ADS)

    Ilatovskiy, Andrey V.; Lebedev, Dmitry V.; Filatov, Michael V.; Grigoriev, Mikhail; Petukhov, Michael G.; Isaev-Ivanov, Vladimir V.

    2011-11-01

    Eukaryotic genome is a highly compacted nucleoprotein complex organized in a hierarchical structure based on nucleosomes. Detailed organization of this structure remains unknown. In the present work we developed algorithms for geometry modeling of the supernucleosomal chromatin structure and for computing distance distribution functions and small-angle neutron scattering (SANS) spectra of the genome-scale (˜106 nucleosomes) chromatin structure at residue resolution. Our physical nucleosome model was based on the mononucleosome crystal structure. A nucleosome was assumed to be rigid within a local coordinate system. Interface parameters between nucleosomes can be set for each nucleosome independently. Pair distance distributions were computed with Monte Carlo simulation. SANS spectra were calculated with Fourier transformation of weighted distance distribution; the concentration of heavy water in solvent and probability of H/D exchange were taken into account. Two main modes of supernucleosomal structure generation were used. In a free generation mode all interface parameters were chosen randomly, whereas nucleosome self-intersections were not allowed. The second generation mode (generation in volume) enabled spherical or cubical wall restrictions. It was shown that calculated SANS spectra for a number of our models were in general agreement with available experimental data.

  19. Percolating bulk-heterostructures from neutron reflectometry and small angle scattering data

    NASA Astrophysics Data System (ADS)

    Olds, Daniel; Duxbury, Phillip

    2013-03-01

    We present a novel algorithm for efficiently calculating the simulated small angle scattering data of any discretized morphological model of arbitrary scale and resolution, referred to as the distribution function method (DFM). Unlike standard SAS fitting methods, the DFM algorithm allows for the calculation of form factors and structure factors from complex nanoscale morphologies commonly encountered in many modern polymeric and nanoparticle based systems, which have no exact analytical corollary. The computational efficiency of the DFM algorithm suggests it's use in morphological model refinement. We will present a number of simple examples to demonstrate the accuracy and limits of the algorithm, followed by an example of incorporation of the DFM algorithm into reverse Monte Carlo structural refinement of bulk-heterojunction two-phase morphologies, such as those commonly found in organic photovoltaic devices. We will show that morphological features introduced via direct incorporation of experimental neutron reflectometry and SANS data to the models has a direct effect on the results of device simulations. The authors thank CORE-CM at Michigan State University for it's funding of this research.

  20. Characterization of colloidal structures during intestinal lipolysis using small-angle neutron scattering.

    PubMed

    Rezhdo, Oljora; Di Maio, Selena; Le, Peisi; Littrell, Kenneth C; Carrier, Rebecca L; Chen, Sow-Hsin

    2017-08-01

    Bile micelles are thought to mediate intestinal absorption, in part by providing a phase into which compounds can partition. Solubilizing capacity of bile micelles is enhanced during the digestion of fat rich food. We hypothesized that the intestinal digestion of triglycerides causes an increase in volume of micelles that can be quantitatively monitored over the course of digestion using small-angle neutron scattering (SANS), and that SANS can enable evaluation of the contribution of each of the components present during digestion to the size of micelles. SANS was used to characterize the size and shape of micelles present prior to and during the in vitro simulated intestinal digestion of a model food-associated lipid, triolein. Pre-lipolysis mixtures of a bile salt and phospholipid simulating bile concentrations in fed conditions were organized in micelles with an average volume of 40 nm(3). During lipolysis, the micelle volume increased 2.5-fold over a 2-h digestion period due to growth in one direction as a result of insertion of monoglycerides and fatty acids. These efforts represent a basis for quantitative mechanistic understanding of changes in solubilizing capacity of the intestinal milieu upon ingestion of a fat-rich meal. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Structural formation of huntingtin-like aggregates probed by small-angle neutron scattering

    SciTech Connect

    Stanley, Christopher B; Perevozchikova, Tatiana; Berthelier-Jung, Valerie M

    2011-01-01

    In several neurodegenerative disorders, including Huntington s disease (HD), aspects concerning the earliest of protein structures that form along the aggregation pathway have increasingly gained attention since these particular species are likely to be neurotoxic. We used time-resolved small-angle neutron scattering (SANS) to probe in solution these transient structures formed by peptides having the N-terminal sequence context of mutant huntingtin (Htt) exon 1. We obtained snapshots of the formed aggregates as the kinetic reaction ensued to yield quantitative information on their size and mass. At the early stage, small precursor species with an initial radius of gyration (Rg) of 16.1 5.9 and average mass of a dimer to trimer were monitored. Structural growth was treated as two modes with a transition from three-dimensional early aggregate formation to two-dimensional fibril growth and association. Our SANS results on the internal structure of the mature fibrils demonstrate loose packing with about 1 peptide per 4.75 -sheet repeat distance, which is shown to be quantitatively consistent with a -helix model. This research provides new insights into the structures forming along the pathway of Htt exon 1 aggregation and should assist in determining the role that precursors play in neuronal toxicity.

  2. Small-angle neutron scattering study of a dense microemulsion system formed with an ionic liquid.

    PubMed

    Kang, T; Qian, S; Smith, G S; Do, C; Heller, W T

    2017-09-12

    Mixtures of water, octane and 1-octanol with 1-tetradecyl-3-methylimidazolium chloride (C14MIM·Cl), often referred to as a surface active ionic liquid (SAIL), form water-in-oil microemulsions that have potential application as extraction media for various metal ions. Here, we present a structural study by small-angle neutron scattering (SANS) of dense microemulsions formed by surfactant-rich mixtures of these four compounds to understand how the SAIL can be used to tune the structures and properties of the microemulsions. The SANS experiments revealed that the microemulsions formed are composed of two phases, a water-in-oil microemulsion and a bicontinuous microemulsion, which becomes the dominant phase at high surfactant concentration. In this concentration regime, the surfactant film becomes more rigid, having a higher bending modulus that results from the parallel stacking of the imidazolium ring of the SAIL. At lower surfactant concentrations, the molecular packing of the SAIL does not change with the water content of the microemulsion. The results presented here correlate well with previously observed changes in the interaction between the IL cation and metal ions (Y. Tong, L. Han and Y. Yang, Ind. Eng. Chem. Res., 2012, 51, 16438-16443), while the capacity of the microemulsion system for water remains high enough for using the system as an extraction medium.

  3. Pore distributions in nanocrystalline metals from small-angle neutron scattering

    SciTech Connect

    Sanders, P.G.; Weertman, J.R.; Eastman, J.A.

    1998-07-24

    Recent upgrades in inert-gas condensation processing equipment have produced nanocrystalline metal samples with high densities and low-impurity levels. Typical Cu and Pd samples have densities {ge}98% of theoretical and oxygen and hydrogen impurity concentrations {le}0.5 at. %. Lower porosity and impurity levels may make it difficult to produce and maintain samples with the smallest nanocrystalline grain sizes. These improved samples were studied by small-angle neutron scattering (SANS) to determine the volume fraction and size distribution of pores. Excellent correlation was obtained between the total volume fraction of pores and the Archimedes density for Pd, signifying that most of the pores were relatively small and in the detectability range of SANS ({approx}1--100 nm). Nanocrystalline Cu is shown to exhibit a wider pore size distribution. For Pd, the average pore sizes were slightly smaller than the average grain size, while for Cu the pore size and grain size were about the same. Both materials exhibited a trend of increasing pore size with increasing grain size. In terms of processing prerequisites, the principal condition for the production of high-density nanocrystalline Cu is an exceptionally clean synthesis environment, while nanocrystalline Pd requires compaction at elevated temperatures. These differences are the result of Cu having both a lower melting point and a greater susceptibility to contamination by gaseous impurities such as oxygen.

  4. Small Angle Neutron Scattering (SANS) Studies on the Structural Evolution of Pyromellitamide Self-assembled Gels

    SciTech Connect

    Scott, Jamieson; Tong, Katie; William, Hamilton; He, Lilin; James, Michael; Thordarson, Pall; Boukhalfa, Sofiane

    2014-10-31

    The kinetics of aggregation of two pyromellitamide gelators; tetrabutyl- (C4) and tetrahexylpyromellitamide (C6), in deuterated cyclohexane has been investigated by small angle neutron scattering (SANS) for up to six days. The purpose of this study was to improve our understanding of how self-assembled gels are formed. Short-term (< 3 hour) time scales revealed multiple phases with the data for the tetrabutylpyromellitamide C4 indicating one dimensional stacking and aggregation corresponding to a multi-fiber braided cluster arrangement that is about 35 Å in diameter. The corresponding tetrahexylpyromellitamide C6 data suggests that the C6 also forms one-dimensional stacks but that these aggregate to a thicker multi-fiber braided cluster that have a diameter of 61.8 Å. Over a longer period of time, the radius, persistence length and contour length all continue to increase in 6 days after cooling. This data suggests that structural changes in self-assembled gels occur over a period exceeding several days and that fairly subtle changes in the structure (e.g. tail-length) can influence the packing of molecules in self-assembled gels on the single-to-few fiber bundle stage.

  5. Small Angle Neutron Scattering (SANS) Studies on the Structural Evolution of Pyromellitamide Self-assembled Gels

    DOE PAGES

    Scott, Jamieson; Tong, Katie; William, Hamilton; ...

    2014-10-31

    The kinetics of aggregation of two pyromellitamide gelators; tetrabutyl- (C4) and tetrahexylpyromellitamide (C6), in deuterated cyclohexane has been investigated by small angle neutron scattering (SANS) for up to six days. The purpose of this study was to improve our understanding of how self-assembled gels are formed. Short-term (< 3 hour) time scales revealed multiple phases with the data for the tetrabutylpyromellitamide C4 indicating one dimensional stacking and aggregation corresponding to a multi-fiber braided cluster arrangement that is about 35 Å in diameter. The corresponding tetrahexylpyromellitamide C6 data suggests that the C6 also forms one-dimensional stacks but that these aggregate tomore » a thicker multi-fiber braided cluster that have a diameter of 61.8 Å. Over a longer period of time, the radius, persistence length and contour length all continue to increase in 6 days after cooling. This data suggests that structural changes in self-assembled gels occur over a period exceeding several days and that fairly subtle changes in the structure (e.g. tail-length) can influence the packing of molecules in self-assembled gels on the single-to-few fiber bundle stage.« less

  6. The polymerization of actin: Structural changes from small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Norman, Alexander I.; Ivkov, Robert; Forbes, Jeffrey G.; Greer, Sandra C.

    2005-10-01

    We present a new analysis of small-angle neutron-scattering data from rabbit muscle actin in the course of the polymerization from G-actin to F-actin as a function of temperature. The data, from Ivkov et al. [J. Chem. Phys. 108, 5599 (1998)], were taken in D2O buffer with Ca2+ as the divalent cation on the G-actin in the presence of ATP and with KCl as the initiating salt. The new analysis of the data using modeling and the method of generalized indirect fourier transform (O. Glatter, GIFT, University of Graz, Austria, http://physchem.kfunigraz.ac.at/sm/) provide shapes and dimensions of the G-actin monomer and of the growing actin oligomer in solution as a function of temperature and salt concentration. This analysis indicates that the G-actin monomer, under the conditions given above, is a sphere 50-54Å in diameter as opposed to the oblate ellipsoid seen by x-ray crystallography. The F-actin dimensions are consistent with x-ray crystal structure determinations.

  7. Small Angle Neutron-Scattering Studies of the Core Structure of Intact Neurosecretory Vesicles.

    NASA Astrophysics Data System (ADS)

    Krueger, Susan Takacs

    Small angle neutron scattering (SANS) was used to study the state of the dense cores within intact neurosecretory vesicles. These vesicles transport the neurophysin proteins, along with their associated hormones, oxytocin or vasopressin, from the posterior pituitary gland to the bloodstream, where the entire vesicle contents are released. Knowledge of the vesicle core structure is important in developing an understanding of this release mechanism. Since the core constituents exist in a dense state at concentrations which cannot be reproduced (in solution) in the laboratory, a new method was developed to determine the core structure from SANS experiments performed on intact neurosecretory vesicles. These studies were complemented by biochemical assays performed to determine the role, if any, played by phospholipids in the interactions between the core constituents. H_2O/D_2 O ratio in the solvent can be adjusted, using the method of contrast variation, such that the scattering due to the vesicle membranes is minimized, thus emphasizing the scattering originating from the cores. The applicability of this method for examining the interior of biological vesicles was tested by performing an initial study on human red blood cells, which are similar in structure to other biological vesicles. Changes in intermolecular hemoglobin interactions, occurring when the ionic strength of the solvent was varied or when the cells were deoxygenated, were examined. The results agreed with those expected for dense protein solutions, indicating that the method developed was suitable for the study of hemoglobin within the cells. Similar SANS studies were then performed on intact neurosecretory vesicles. The experimental results were inconsistent with model calculations which assumed that the cores consisted of small, densely-packed particles or large, globular aggregates. Although a unique model could not be determined, the data suggest that the core constituents form long aggregates of

  8. Monte-Carlo simulation of an ultra small-angle neutron scattering instrument based on Soller slits

    SciTech Connect

    Rieker, T.; Hubbard, P.

    1997-09-01

    Monte Carlo simulations are used to investigate an ultra small-angle neutron scattering instrument for use at a pulsed source based on a Soller slit collimator and analyzer. The simulations show that for a q{sub min} of {approximately}le-4 {angstrom}{sup -1} (15 {angstrom} neutrons) a few tenths of a percent of the incident flux is transmitted through both collimators at q=0.

  9. Parameterization of structures in HE composites using surrogate materials: A small angle neutron scattering investigation

    SciTech Connect

    Mang, J.T.; Hjelm, R.P.; Skidmore, C.B.; Howe, P.M.

    1996-07-01

    High explosive materials used in the nuclear stockpile are composites of crystalline high explosives (HE) with binder materials, such as Estane. In such materials, there are naturally occurring density fluctuations (defects) due to cracks, internal (in the HE) and external (in the binder) voids and other artifacts of preparation. Changes in such defects due to material aging can affect the response of explosives due to shock, impact and thermal loading. Modeling efforts are attempting to provide quantitative descriptions of explosive response from the lowest ignition thresholds to the development of full blown detonations and explosions, however, adequate descriptions of these processes require accurate measurements of a number of structural parameters of the HE composite. Since different defects are believed to affect explosive sensitivity in different ways it is necessary to quantitatively differentiate between defect types. The authors report here preliminary results of SANS measurements on surrogates for HE materials. The objective of these measurements was to develop methodologies using SANS techniques to parameterize internal void size distributions in a surrogate material, sugar, to simulate an HE used in the stockpile, HMX. Sugar is a natural choice as a surrogate material, as it has the same crystal structure, has similar intragranular voids and has similar mechanical properties as HMX. It is used extensively as a mock material for explosives. Samples were used with two void size distributions: one with a sufficiently small mean particle size that only small occluded voids are present in significant concentrations, and one where the void sizes could be larger. By using methods in small-angle neutron scattering, they were able to isolate the scattering arising from particle-liquid interfaces and internal voids.

  10. Microstructure of beta-lactoglobulin/pectin coacervates studied by small-angle neutron scattering.

    PubMed

    Wang, Xiaoyong; Li, Yunqi; Wang, Yu-Wen; Lal, Jyotsana; Huang, Qingrong

    2007-01-25

    Small-angle neutron scattering (SANS) has been used to investigate the microstructure of beta-lactoglobulin/pectin coacervates prepared by different initial protein/polysaccharide weight ratio (r), sodium chloride concentration (C(NaCl)), and pectin charge density. The higher r and higher pectin charge density lead to higher scattering intensity at small q range (0.007 Angstrom(-1) < q < 0.02 Angstrom(-1)), suggesting that the charges of pectin chains are screened significantly by the binding of oppositely charged protein molecules, leading to a tighter aggregation of pectin chains. On the other hand, the appearance of a shoulder peak at intermediate q range (0.04 Angstrom(-1) < q < 0.2 Angstrom(-1)) is used to interpret the formation of protein domains in beta-lactoglobulin/pectin coacervates. At C(NaCl) = 0.1 M, the coacervate of beta-lactoglobulin and pectin A does not show a shoulder peak at intermediate q range at r = 10:1, suggesting that protein molecules are separately bound on pectin chains. However, a shoulder peak appears at intermediate q range at r = 20:1 and 30:1, and the average protein domain size estimated from the shoulder peak position is 7.2 and 8.5 nm, respectively, for these two coacervates. When C(NaCl) increases from 0.05 to 0.2 M, the shoulder peak shifts toward smaller q and becomes broader, indicating that the addition of a higher amount of salt leads to a more heterogeneous coacervate structure. Pectin B with a lower linear charge density favors the formation of larger protein domains. The formation of protein domains in beta-lactoglobulin/pectin coacervates is partially ascribed to the self-aggregation of beta-lactoglobulin molecules. Two kinds of microstructures of beta-lactoglobulin/pectin coacervates with and without observable protein domains have been proposed.

  11. Magnetic scattering in the simultaneous measurement of small-angle neutron scattering and Bragg edge transmission from steel.

    PubMed

    Oba, Yojiro; Morooka, Satoshi; Ohishi, Kazuki; Sato, Nobuhiro; Inoue, Rintaro; Adachi, Nozomu; Suzuki, Jun-Ichi; Tsuchiyama, Toshihiro; Gilbert, Elliot Paul; Sugiyama, Masaaki

    2016-10-01

    Pulsed neutron sources enable the simultaneous measurement of small-angle neutron scattering (SANS) and Bragg edge transmission. This simultaneous measurement is useful for microstructural characterization in steel. Since most steels are ferromagnetic, magnetic scattering contributions should be considered in both SANS and Bragg edge transmission analyses. An expression for the magnetic scattering contribution to Bragg edge transmission analysis has been derived. The analysis using this expression was applied to Cu steel. The ferrite crystallite size estimated from this Bragg edge transmission analysis with the magnetic scattering contribution was larger than that estimated using conventional expressions. This result indicates that magnetic scattering has to be taken into account for quantitative Bragg edge transmission analysis. In the SANS analysis, the ratio of magnetic to nuclear scattering contributions revealed that the precipitates consist of body-centered cubic Cu0.7Fe0.3 and pure Cu, which probably has 9R structure including elastic strain and vacancies. These results show that effective use of the magnetic scattering contribution allows detailed analyses of steel microstructure.

  12. Magnetic scattering in the simultaneous measurement of small-angle neutron scattering and Bragg edge transmission from steel1

    PubMed Central

    Oba, Yojiro; Morooka, Satoshi; Ohishi, Kazuki; Sato, Nobuhiro; Inoue, Rintaro; Adachi, Nozomu; Suzuki, Jun-ichi; Tsuchiyama, Toshihiro; Gilbert, Elliot Paul; Sugiyama, Masaaki

    2016-01-01

    Pulsed neutron sources enable the simultaneous measurement of small-angle neutron scattering (SANS) and Bragg edge transmission. This simultaneous measurement is useful for microstructural characterization in steel. Since most steels are ferromagnetic, magnetic scattering contributions should be considered in both SANS and Bragg edge transmission analyses. An expression for the magnetic scattering contribution to Bragg edge transmission analysis has been derived. The analysis using this expression was applied to Cu steel. The ferrite crystallite size estimated from this Bragg edge transmission analysis with the magnetic scattering contribution was larger than that estimated using conventional expressions. This result indicates that magnetic scattering has to be taken into account for quantitative Bragg edge transmission analysis. In the SANS analysis, the ratio of magnetic to nuclear scattering contributions revealed that the precipitates consist of body-centered cubic Cu0.7Fe0.3 and pure Cu, which probably has 9R structure including elastic strain and vacancies. These results show that effective use of the magnetic scattering contribution allows detailed analyses of steel microstructure. PMID:27738416

  13. Field-induced self-assembly of iron oxide nanoparticles investigated using small-angle neutron scattering.

    PubMed

    Fu, Zhendong; Xiao, Yinguo; Feoktystov, Artem; Pipich, Vitaliy; Appavou, Marie-Sousai; Su, Yixi; Feng, Erxi; Jin, Wentao; Brückel, Thomas

    2016-11-03

    The magnetic-field-induced assembly of magnetic nanoparticles (NPs) provides a unique and flexible strategy in the design and fabrication of functional nanostructures and devices. We have investigated the field-induced self-assembly of core-shell iron oxide NPs dispersed in toluene by means of small-angle neutron scattering (SANS). The form factor of the core-shell NPs was characterized and analyzed using SANS with polarized neutrons. Large-scale aggregates of iron oxide NPs formed above 0.02 T as indicated by very-small-angle neutron scattering measurements. A three-dimensional long-range ordered superlattice of iron oxide NPs was revealed under the application of a moderate magnetic field. The crystal structure of the superlattice has been identified to be face-centred cubic.

  14. Structure of spontaneously formed solid-electrolyte interphase on lithiated graphite determined using small-angle neutron scattering

    DOE PAGES

    Sacci, Robert L.; Banuelos, Jose Leobardo; Veith, Gabriel M.; ...

    2015-03-25

    We report the first small-angle neutron scattering of a chemically formed solid-electrolyte interphase from LixC6 reacting with ethylene carbonate/dimethyl carbon solvent. This provides a different and perhaps simpler view of SEI formation than the usual electrochemically-driven reaction. We show that an organic layer coats the graphite particles filling in micro-pores and is polymeric in nature being 1-3 nm thick. We used inelastic neutron scattering to probe the chemistry, and we found that the SEI showed similar inelastic scattering to polyethylene oxide.

  15. Small-Angle Neutron Scattering Studies of Magnetic Correlation Lengths in Nanoparticle Assemblies

    NASA Astrophysics Data System (ADS)

    Majetich, Sara

    2009-03-01

    Small-angle neutron scattering (SANS) measurements of ordered arrays of surfactant-coated magnetic nanoparticle reveal characteristic length scales associated with interparticle and intraparticle magnetic ordering. The high degree of uniformity in the monodisperse nanoparticle size and spacing leads to a pronounced diffraction peak and allows for a straightforward determination of these length scales [1]. There are notable differences in these length scales depending on the particle moment, which depends on the material (Fe, Co, Fe3O4) and diameter, and also on whether the metal particle core is surrounded by an oxide shell. For 8.5 nm particles containing an Fe core and thick Fe3O4 shell, evidence of a spin flop phase is seen in the magnetite shell when a field is applied , but not when the shell thickness is ˜0.5 nm [2]. 8.0 nm particles with an e-Co core and 0.75 nm CoO shell show no exchange bias effects while similar particles with a 2 nm thick shell so significant training effects below 90 K. Polarized SANS studied of 7 nm Fe3O4 nanoparticle assemblies show the ability to resolve the magnetization components in 3D. [4pt] [1] M. Sachan, C. Bonnoit, S. A. Majetich, Y. Ijiri, P. O. Mensah-Bonsu, J. A. Borchers, and J. J. Rhyne, Appl. Phys. Lett. 92, 152503 (2008). [0pt] [2] Yumi Ijiri, Christopher V. Kelly, Julie A. Borchers, James J. Rhyne, Dorothy F. Farrell, Sara A. Majetich, Appl. Phys. Lett. 86, 243102-243104 (2005). [0pt] [3] K. L. Krycka, R. Booth, J. A. Borchers, W. C. Chen, C. Conlon, T. Gentile, C. Hogg, Y. Ijiri, M. Laver, B. B. Maranville, S. A. Majetich, J. Rhyne, and S. M. Watson, Physica B (submitted).

  16. Morphology of fast-tumbling bicelles: a small angle neutron scattering and NMR study.

    PubMed

    Luchette, P A; Vetman, T N; Prosser, R S; Hancock, R E; Nieh, M P; Glinka, C J; Krueger, S; Katsaras, J

    2001-08-06

    Bilayered micelles, or bicelles, which consist of a mixture of long- and short-chain phospholipids, are a popular model membrane system. Depending on composition, concentration, and temperature, bicelle mixtures may adopt an isotropic phase or form an aligned phase in magnetic fields. Well-resolved (1)H NMR spectra are observed in the isotropic or so-called fast-tumbling bicelle phase, over the range of temperatures investigated (10-40 degrees C), for molar ratios of long-chain lipid to short-chain lipid between 0.20 and 1.0. Small angle neutron scattering data of this phase are consistent with the model in which bicelles were proposed to be disk-shaped. The experimentally determined dimensions are roughly consistent with the predictions of R.R. Vold and R.S. Prosser (J. Magn. Reson. B 113 (1996)). Differential paramagnetic shifts of head group resonances of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC), induced by the addition of Eu(3+), are also consistent with the bicelle model in which DHPC is believed to be primarily sequestered to bicelle rims. Selective irradiation of the DHPC aliphatic methyl resonances results in no detectable magnetization transfer to the corresponding DMPC methyl resonances (and vice versa) in bicelles, which also suggests that DHPC and DMPC are largely sequestered in the bicelle. Finally, (1)H spectra of the antibacterial peptide indolicidin (ILPWKWPWWPWRR-NH(2)) are compared, in a DPC micellar phase and the above fast-tumbling bicellar phases for a variety of compositions. The spectra exhibit adequate resolution and improved dispersion of amide and aromatic resonances in certain bicelle mixtures.

  17. Tensile Properties and Small-Angle Neutron Scattering Investigation of Stereoblock Elastomeric Polypropylene

    SciTech Connect

    Pople, John A

    2002-08-06

    Elastomeric polypropylene (ePP) produced from unbridged 2-arylindene metallocene catalysts was studied by uniaxial tensile and small-angle neutron scattering (SANS) techniques. The ePP can be separated into three fractions by successive boiling-solvent fractionation method to yield: a low-tacticity fraction soluble in ether (ES), an intermediate-tacticity fraction soluble in heptane (HS), and a high-tacticity fraction insoluble in heptane (HI). Tensile properties of ePP were compared to its solvent fractions, and the role of each solvent fraction residing within ePP was investigated by blending 5 weight % deuterated fraction with ePP. The tensile properties of each fraction vary considerably, exhibiting properties from a weak gum elastomer for ES, to a semi-crystalline thermoplastic for HI. The intermediate-tacticity HS fraction exhibits elastic properties similar to the parent elastomer (ePP). In the melt at 160 C, SANS shows that all deuterated fractions are homogeneously mixed with ePP in a one-phase system. At 25 C upon a slow cooling from the melt, the low-tacticity fraction is preferentially segregated in the amorphous domains induced by different crystallization temperatures and kinetics of the deuterated ES and high-tacticity components. The high-tacticity component within ePP (dHI-ePP) retains its plastic properties in the blend. Despite its low crystallinity ({le} 2%), the low-tacticity fraction can co-crystallize with the crystalline matrix. The dES-ePP shows little or no relaxation when held under strain and recovers readily upon the release of stress.

  18. Small-angle neutron scattering study of structure and kinetics of temperature-induced protein gelation.

    PubMed

    Chodankar, S; Aswal, V K; Kohlbrecher, J; Vavrin, R; Wagh, A G

    2009-02-01

    The phase diagram, structural evolution, and kinetics of temperature-induced protein gelation of protein Bovine Serum Albumin (BSA) have been studied as a function of solution pH and protein concentration. The protein gelation temperature represents the onset of turbidity in the protein solution, which increases significantly with increasing pH beyond the isoelectric pH of the protein molecule. On the other hand, the gelation temperature decreases with an increase in protein concentration only in the low-protein-concentration regime and shows a small increasing trend at higher protein concentrations. The structural evolution and kinetics of protein gelation have been studied using small-angle neutron scattering. The structure of the protein molecule remains stable up to temperatures very close to the gelation temperature. On increasing the temperature above the gelation temperature, the protein solution exhibits a fractal structure, an indication of gel formation due to aggregation. The fractal dimension of the gel increases with increasing temperature, suggesting an increase in branching between the aggregates, which leads to stronger gels. The increase in both solution pH and protein concentration is found to delay the growth in the fractal structure and its saturation. The kinetics of gelation has been studied using the temperature-jump process of heating. It is found that the structure of the protein gels remains invariant after the heating time ( approximately 1 min), indicating a rapid formation of gel structure within this time. The protein gels prepared through gradual and temperature-jump heating routes do not always show the same structure. In particular, at higher temperatures (e.g., 85 degrees C ), while gradual heating shows a fractal structure, there is collapse of such fractal structure during temperature-jump heating.

  19. Effective interactions in lysozyme aqueous solutions: A small-angle neutron scattering and computer simulation study

    NASA Astrophysics Data System (ADS)

    Abramo, M. C.; Caccamo, C.; Costa, D.; Pellicane, G.; Ruberto, R.; Wanderlingh, U.

    2012-01-01

    We report protein-protein structure factors of aqueous lysozyme solutions at different pH and ionic strengths, as determined by small-angle neutron scattering experiments. The observed upturn of the structure factor at small wavevectors, as the pH increases, marks a crossover between two different regimes, one dominated by repulsive forces, and another one where attractive interactions become prominent, with the ensuing development of enhanced density fluctuations. In order to rationalize such experimental outcome from a microscopic viewpoint, we have carried out extensive simulations of different coarse-grained models. We have first studied a model in which macromolecules are described as soft spheres interacting through an attractive r-6 potential, plus embedded pH-dependent discrete charges; we show that the uprise undergone by the structure factor is qualitatively predicted. We have then studied a Derjaguin-Landau-Verwey-Overbeek (DLVO) model, in which only central interactions are advocated; we demonstrate that this model leads to a protein-rich/protein-poor coexistence curve that agrees quite well with the experimental counterpart; experimental correlations are instead reproduced only at low pH and ionic strengths. We have finally investigated a third, "mixed" model in which the central attractive term of the DLVO potential is imported within the distributed-charge approach; it turns out that the different balance of interactions, with a much shorter-range attractive contribution, leads in this latter case to an improved agreement with the experimental crossover. We discuss the relationship between experimental correlations, phase coexistence, and features of effective interactions, as well as possible paths toward a quantitative prediction of structural properties of real lysozyme solutions.

  20. Structure and properties of aqueous methylcellulose gels by small-angle neutron scattering.

    PubMed

    Chatterjee, Tirtha; Nakatani, Alan I; Adden, Roland; Brackhagen, Meinolf; Redwine, David; Shen, Hongwei; Li, Yongfu; Wilson, Tricia; Sammler, Robert L

    2012-10-08

    Cold, semidilute, aqueous solutions of methylcellulose (MC) are known to undergo thermoreversible gelation when warmed. This study focuses on two MC materials with much different gelation performance (gel temperature and hot gel modulus) even though they have similar metrics of their coarse-grained chemical structure (degree-of-methylether substitution and molecular weight distribution). Small-angle neutron scattering (SANS) experiments were conducted to probe the structure of the aqueous MC materials at pre- and postgel temperatures. One material (MC1, higher gel temperature) exhibited a single almost temperature-insensitive gel characteristic length scale (ζ(c) = 1090 ± 50 Å) at postgelation temperatures. This length scale is thought to be the gel blob size between network junctions. It also coincides with the length scale between entanglement sites measured with rheology studies at pregel temperatures. The other material (MC2, lower gel temperature) exhibited two distinct length scales at all temperatures. The larger length scale decreased as temperature increased. Its value (ζ(c1) = 1046 ± 19 Å) at the lowest pregel temperature was indistinguishable from that measured for MC1, and reached a limiting value (ζ(c1) = 450 ± 19 Å) at high temperature. The smaller length scale (ζ(c2) = 120 to 240 Å) increased slightly as temperature increased, but remained on the order of the chain persistence length (130 Å) measured at pregel temperatures. The smaller blob size (ζ(c1)) of MC2 suggests a higher bond energy or a stiffer connectivity between network junctions. Moreover, the number density of these blobs, at the same reduced temperature with respect to the gel temperature, is orders of magnitude higher for the MC2 gels. Presumably, the smaller gel length scale and higher number density lead to higher hot gel modulus for the low gel temperature material.

  1. Small-angle neutron scattering studies of hemoglobin confined inside silica tubes of varying sizes.

    PubMed

    Mandal, Soumit S; Cristiglio, Viviana; Lindner, Peter; Bhattacharyya, Aninda J

    2014-02-03

    In addition to the chemical nature of the surface, the dimensions of the confining host exert a significant influence on confined protein structures; this results in immense biological implications, especially those concerning the enzymatic activities of the protein. This study probes the structure of hemoglobin (Hb), a model protein, confined inside silica tubes with pore diameters that vary by one order of magnitude (≈20-200 nm). The effect of confinement on the protein structure is probed by comparison with the structure of the protein in solution. Small-angle neutron scattering (SANS), which provides information on protein tertiary and quaternary structures, is employed to study the influence of the tube pore diameter on the structure and configuration of the confined protein in detail. Confinement significantly influences the structural stability of Hb and the structure depends on the Si-tube pore diameter. The high radius of gyration (Rg) and polydispersity of Hb in the 20 nm diameter Si-tube indicates that Hb undergoes a significant amount of aggregation. However, for Si-tube diameters greater or equal to 100 nm, the Rg of Hb is found to be in very close proximity to that obtained from the protein data bank (PDB) reported structure (Rg of native Hb=23.8 Å). This strongly indicates that the protein has a preference for the more native-like non-aggregated state if confined inside tubes of diameter greater or equal to 100 nm. Further insight into the Hb structure is obtained from the distance distribution function, p(r), and ab initio models calculated from the SANS patterns. These also suggest that the Si-tube size is a key parameter for protein stability and structure. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Nanostructure in block copolymer solutions: Rheology and small-angle neutron scattering

    SciTech Connect

    Habas, Jean-Pierre; Pavie, Emmanuel; Perreur, Christelle; Lapp, Alain; Peyrelasse, Jean

    2004-12-01

    Triblock copolymers composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) present an amphiphilic character in aqueous solutions. Since PPO is less hydrophilic than PEO and since their solubilities decrease when the temperature increases, the copolymers self-assemble spontaneously, forming micelles at moderate temperatures. For higher temperatures or concentrations, the copolymers or the micelles are ordered because of repulsive interactions and form lyotropic liquid crystalline phases. These are phases of very great viscosity with the aspect of gels, and transitions between different crystalline phases can occur at fixed concentration during an increase of temperature. We studied solutions of three different copolymers. The first two have a star structure. They are both composed of four branches (EO){sub x}(PO){sub y} fixed on an ethylene diamine, but differ by the values of x and y. Their commercial name is Tetronic 908 (x=114, y=21) and Tetronic 704 (x=16, y=18). The third copolymer (EO){sub 37}(PO){sub 56}(EO){sub 37} is linear and is known under the name of Pluronic P105. The measurements of the shear complex elastic modulus according to the temperature is used to determine the temperatures of the different transitions. Then, small-angle neutron scattering on samples under flow and true crystallographic arguments make it possible to identify the nature of the crystalline phases. For the systems studied, we show that the branched copolymers form only one type of liquid crystalline phase, which is bcc for the T908 and lamellar for the T704. For the linear copolymer, it is possible to identify three transitions: micellar solution to hexagonal phase, hexagonal phase to body-centered cubic phase, and finally body-centered cubic phase to lamellar phase.

  3. Effective interactions in lysozyme aqueous solutions: a small-angle neutron scattering and computer simulation study.

    PubMed

    Abramo, M C; Caccamo, C; Costa, D; Pellicane, G; Ruberto, R; Wanderlingh, U

    2012-01-21

    We report protein-protein structure factors of aqueous lysozyme solutions at different pH and ionic strengths, as determined by small-angle neutron scattering experiments. The observed upturn of the structure factor at small wavevectors, as the pH increases, marks a crossover between two different regimes, one dominated by repulsive forces, and another one where attractive interactions become prominent, with the ensuing development of enhanced density fluctuations. In order to rationalize such experimental outcome from a microscopic viewpoint, we have carried out extensive simulations of different coarse-grained models. We have first studied a model in which macromolecules are described as soft spheres interacting through an attractive r(-6) potential, plus embedded pH-dependent discrete charges; we show that the uprise undergone by the structure factor is qualitatively predicted. We have then studied a Derjaguin-Landau-Verwey-Overbeek (DLVO) model, in which only central interactions are advocated; we demonstrate that this model leads to a protein-rich/protein-poor coexistence curve that agrees quite well with the experimental counterpart; experimental correlations are instead reproduced only at low pH and ionic strengths. We have finally investigated a third, "mixed" model in which the central attractive term of the DLVO potential is imported within the distributed-charge approach; it turns out that the different balance of interactions, with a much shorter-range attractive contribution, leads in this latter case to an improved agreement with the experimental crossover. We discuss the relationship between experimental correlations, phase coexistence, and features of effective interactions, as well as possible paths toward a quantitative prediction of structural properties of real lysozyme solutions.

  4. Distribution of transport current in a type-II superconductor studied by small-angle neutron scattering.

    PubMed

    Pautrat, A; Goupil, C; Simon, Ch; Charalambous, D; Forgan, E M; Lazard, G; Mathieu, P; Brûlet, A

    2003-02-28

    We report small-angle neutron scattering measurements on the vortex lattice in a PbIn polycrystal in the presence of an applied current. Using the rocking curves as a probe of the distribution of current in the sample, we observe that vortex pinning is due to the surface roughness. This leads to a surface current that persists in the flux-flow region. We show the influence of surface treatments on the distribution of this current.

  5. Structural studies of Neurospora crassa LPMO9D and redox partner CDHIIA using neutron crystallography and small-angle scattering.

    PubMed

    Bodenheimer, Annette M; O'Dell, William B; Stanley, Christopher B; Meilleur, Flora

    2017-08-07

    Sensitivity to hydrogen/deuterium and lack of observable radiation damage makes cold neutrons an ideal probe the structural studies of proteins with highly photosensitive groups such as the copper center of lytic polysaccharide monooxygenases (LPMOs) and flavin adenine dinucleotide (FAD) and heme redox cofactors of cellobiose dehydrogenases (CDHs). Here, neutron crystallography and small-angle neutron scattering are used to investigate Neurospora crassa LPMO9D (NcLPMO9D) and CDHIIA (NcCDHIIA), respectively. The presence of LPMO greatly enhances the efficiency of commercial glycoside hydrolase cocktails in the depolymerization of cellulose. LPMOs can receive electrons from CDHs to activate molecular dioxygen for the oxidation of cellulose resulting in chain cleavage and disruption of local crystallinity. Using neutron protein crystallography, the hydrogen/deuterium atoms of NcLPMO9D could be located throughout the structure. At the copper active site, the protonation states of the side chains of His1, His84, His157 and Tyr168, and the orientation of water molecules could be determined. Small-angle neutron scattering measurements provided low resolution models of NcCDHIIA with both the dehydrogenase and cytochrome domains in oxidized states that exhibited elongated conformations. This work demonstrates the suitability of neutron diffraction and scattering for characterizing enzymes critical to oxidative cellulose deconstruction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Carbide precipitates in solution-quenched PH13-8 Mo stainless steel: A small-angle neutron scattering investigation

    NASA Astrophysics Data System (ADS)

    Sen, D.; Patra, A. K.; Mazumder, S.; Mittra, J.; Dey, G. K.; de, P. K.

    2004-08-01

    This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel. From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical particle model with a locked aspect ratio.

  7. Magnetic-field-dependent small-angle neutron scattering on random anisotropy ferromagnets

    NASA Astrophysics Data System (ADS)

    Michels, Andreas; Weissmüller, Jörg

    2008-06-01

    We report on the recently developed technique of magnetic-field-dependent small-angle neutron scattering (SANS), with attention to bulk ferromagnets exhibiting random magnetic anisotropy. In these materials, the various magnetic anisotropy fields (magnetocrystalline, magnetoelastic, and/or magnetostatic in origin) perturb the perfectly parallel spin alignment of the idealized ferromagnetic state. By varying the applied magnetic field, one can control one of the ordering terms which competes with the above-mentioned perturbing fields. Experiments which explore the ensuing reaction of the magnetization will therefore provide information not only on the field-dependent spin structure but, importantly, on the underlying magnetic interaction terms. This strategy, which underlies conventional studies of hysteresis loops in magnetometry, is here combined with magnetic SANS. While magnetometry generally records only a single scalar quantity, the integral magnetization, SANS provides access to a vastly richer data set, the Fourier spectrum of the response of the spin system as a function of the magnitude and orientation of the wave vector. The required data-analysis procedures have recently been established, and experiments on a number of magnetic materials, mostly nanocrystalline or nanocomposite metals, have been reported. Here, we summarize the theory of magnetic-field-dependent SANS along with the underlying description of random anisotropy magnets by micromagnetic theory. We review experiments which have explored the magnetic interaction parameters, the value of the exchange-stiffness constant as well as the Fourier components of the magnetic anisotropy field and of the magnetostatic stray field. A model-independent approach, based on the experimental autocorrelation function of the spin misalignment, provides access to the characteristic length of the spin misalignment. The field dependence of this quantity is in quantitative agreement with the predictions of

  8. Small-angle neutron scattering data on C{sub 60} clusters in weakly polar solutions of fullerenes

    SciTech Connect

    Tropin, T. V. Avdeev, M. V.; Aksenov, V. L.

    2007-05-15

    Solutions of fullerence C{sub 60} in carbon disulfide CS{sub 2} have been investigated by small-angle neutron scattering. Combination of solubility, contrast, and incoherent scattering make it possible to measure and analyze the relatively small scattering cross section of this system. Along with single fullerene molecules, a small amount of large fullerene clusters (more than 100 A in size) is found in these solutions. The formation of these clusters depends on the procedure of solution preparation. The size distribution functions of clusters are compared with the results of the phenomenological cluster model of fullerene solubility.

  9. Preparing monodisperse macromolecular samples for successful biological small-angle X-ray and neutron-scattering experiments.

    PubMed

    Jeffries, Cy M; Graewert, Melissa A; Blanchet, Clément E; Langley, David B; Whitten, Andrew E; Svergun, Dmitri I

    2016-11-01

    Small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) are techniques used to extract structural parameters and determine the overall structures and shapes of biological macromolecules, complexes and assemblies in solution. The scattering intensities measured from a sample contain contributions from all atoms within the illuminated sample volume, including the solvent and buffer components, as well as the macromolecules of interest. To obtain structural information, it is essential to prepare an exactly matched solvent blank so that background scattering contributions can be accurately subtracted from the sample scattering to obtain the net scattering from the macromolecules in the sample. In addition, sample heterogeneity caused by contaminants, aggregates, mismatched solvents, radiation damage or other factors can severely influence and complicate data analysis, so it is essential that the samples be pure and monodisperse for the duration of the experiment. This protocol outlines the basic physics of SAXS and SANS, and it reveals how the underlying conceptual principles of the techniques ultimately 'translate' into practical laboratory guidance for the production of samples of sufficiently high quality for scattering experiments. The procedure describes how to prepare and characterize protein and nucleic acid samples for both SAXS and SANS using gel electrophoresis, size-exclusion chromatography (SEC) and light scattering. Also included are procedures that are specific to X-rays (in-line SEC-SAXS) and neutrons, specifically preparing samples for contrast matching or variation experiments and deuterium labeling of proteins.

  10. Small angle neutron scattering modeling of copper-rich precipitates in steel

    SciTech Connect

    Spooner, S.

    1997-11-01

    The magnetic to nuclear scattering intensity ratio observed in the scattering from copper rich precipitates in irradiated pressure vessel steels is much smaller than the value of 11.4 expected for a pure copper precipitate in iron. A model for precipitates in pressure vessel steels which matches the observed scattering typically incorporates manganese, nickel, silicon and other elements and it is assumed that the precipitate is non-magnetic. In the present work consideration is given to the effect of composition gradients and ferromagnetic penetration into the precipitate on the small angle scattering cross section for copper rich clusters as distinguished from conventional precipitates. The calculation is an extension of a scattering model for micelles which consist of shells of varying scattering density. A discrepancy between recent SANS scattering experiments on pressure vessel steels was found to be related to applied magnetic field strength. The assumption of cluster structure and its relation to atom probe FIM findings as well as the effects of insufficient field for magnetic saturation is discussed.

  11. Small angle neutron scattering modeling of copper-rich precipitates in steel

    SciTech Connect

    Spooner, S.

    1997-11-01

    The magnetic-to-nuclear scattering intensity ratio observed in the scattering from copper-rich precipitates in irradiated pressure vessel steels is much smaller than the value of 11.4 expected for a pure copper precipitate in iron. A model for precipitates in pressure vessel steels which matches the observed scattering typically incorporates manganese, nickel, silicon and other elements and it is assumed that the precipitate is non-magnetic. In the present work consideration is given to the effect of composition gradients and ferromagnetic penetration into the precipitate on the small angle scattering cross section for copper-rich clusters as distinguished from conventional precipitates. The calculation is an extension of a scattering model for micelles which consist of shells of varying scattering density. A discrepancy between recent SANS scattering experiments on pressure vessel shells was found to be related to applied magnetic field strength. The assumption of cluster structure and its relation to atom probe FIM findings as well as the effects of insufficient field for magnetic saturation is discussed.

  12. Investigation of microstructural evolution under neutron irradiation in Eurofer97 steel by means of small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Lindau, R.; May, R. P.; Möslang, A.; Valli, M.

    2009-04-01

    Small-angle neutron scattering (SANS) has been utilized to investigate in Eurofer97 steel (9Cr, 0.01C, 1W, 0.2V Fe bal wt%) the microstructural effect of neutron irradiation at 300 °C up to a dose level of 8.4 dpa. For each irradiated sample an unirradiated reference was measured to distinguish as accurately as possible the actual effect of the neutron irradiation. The SANS measurements were carried out at the D22 diffractometer at the High-Flux Reactor of the Institut Max von Laue-Paul Langevin, Grenoble, France. Analysing separately the nuclear and magnetic SANS components obtained after subtraction of the reference from the irradiated sample it appears that the microstructural inhomogeneities produced under such irradiation conditions are non-magnetic ones, such as microvoids. Their size distributions are presented and compared with those previously obtained for the same steel irradiated at 2.5 dpa: with increasing the dose, the volume fraction is increased by a factor of 2 roughly, while the average size of these inhomogeneities remains nearly unchanged.

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

    SciTech Connect

    Kiselev, M. A. Zemlyanaya, E. V.; Zhabitskaya, E. I.; Aksenov, V. L.

    2015-01-15

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

  14. Strain induced directional coarsening in nickel based superalloys: Investigation on kinetics using the small angle neutron scattering (SANS) technique

    SciTech Connect

    Veron, M.; Bastie, P.

    1997-08-01

    Using the small angle neutron scattering technique, the authors have observed rafting in nickel based single crystal superalloys. Kinetics of morphological evolution of the precipitates have been studied in situ. Therefore the authors used a special furnace designed for the ageing of prestrained specimens under a neutron beam. The evolution of both the precipitate aspect ratio and the distance between precipitates confirms the importance of strain in the directional coarsening process. Results are presented and discussed regarding kinetics and microstructural aspects. In such conditions, rafts seem to be different from those obtained after a creep test.

  15. A portable hydro-thermo-mechanical loading cell for in situ small angle neutron scattering studies of proton exchange membranes.

    PubMed

    Yu, Dunji; An, Ke; Gao, Carrie Y; Heller, William T; Chen, Xu

    2013-10-01

    A portable hydro-thermo-mechanical loading cell has been designed to enable in situ small angle neutron scattering (SANS) studies of proton exchange membranes (PEMs) under immersed tensile loadings at different temperatures. The cell consists of three main parts as follows: a letter-paper-size motor-driven mechanical load frame, a SANS friendly reservoir that provides stable immersed and thermal sample conditions, and a data acquisition and control system. The ex situ tensile tests of Nafion 212 membranes demonstrated a satisfactory thermo-mechanical testing performance of the cell for either dry or immersed conditions at elevated temperatures. The in situ SANS tensile measurements on the Nafion 212 membranes immersed in D2O at 70 °C proved the feasibility and capability of the cell for small angle scattering study on deformation behaviors of PEM and other polymer materials under hydro-thermo-mechanical loading.

  16. A Study of Cross-linked Regions of Poly(Vinyl Alcohol) Gels by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

    2011-07-01

    A poly(vinyl alcohol)-borax cross-linked hydrogel has been studied by Small Angle Neutron Scattering as a function of borax concentration in the wave-vector transfer (Q) range of 0.017 Å-1 to 0.36 Å-1. It is found that as the concentration of borax increases, so does the intensity of scattering in this range. Beyond a borax concentration of 2 mg/ml, the increase in cross-linked PVA chains leads to cross-linked units larger than 150 Å as evidenced by a reduction in intensity in the lower Q region.

  17. Small-Angle Neutron Scattering and Neutron Spin Echo Characterization of Monoclonal Antibody Self-Associations at High Concentrations

    NASA Astrophysics Data System (ADS)

    Yearley, Eric; Zarraga, Isidro (Dan); Godfrin, Paul (Doug); Perevozchikova, Tatiana; Wagner, Norman; Liu, Yun

    2013-03-01

    Concentrated therapeutic protein formulations offer numerous delivery and stability challenges. In particular, it has been found that several therapeutic proteins exhibit a large increase in viscosity as a function of concentration that may be dependent on the protein-protein interactions. Small-Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) investigations have been performed to probe the protein-protein interactions and diffusive properties of highly concentrated MAbs. The SANS data demonstrate that the inter-particle interactions for a highly viscous MAb at high concentrations (MAb1) are highly attractive, anisotropic and change significantly with concentration while the viscosity and interactions do not differ considerably for MAb2. The NSE results furthermore indicate that MAb1 and MAb2 have strong concentration dependencies of dynamics at high Q that are correlated to the translational motion of the proteins. Finally, it has also been revealed that the individual MAb1 proteins form small clusters at high concentrations in contrast to the MAb2 proteins, which are well-dispersed. It is proposed that the formation of these clusters is the primary cause of the dramatic increase in viscosity of MAb1 in crowded or concentrated environments.

  18. KWS-3, the new focusing-mirror ultra small-angle neutron scattering instrument and reflectometer at Jülich

    NASA Astrophysics Data System (ADS)

    Kentzinger, E.; Dohmen, L.; Alefeld, B.; Rücker, U.; Stellbrink, J.; Ioffe, A.; Richter, D.; Brückel, Th.

    2004-07-01

    In Jülich, a new high-resolution small-angle neutron scattering (SANS) instrument and reflectometer has been built. The principle of this instrument is a one-to-one image of an entrance aperture on a 2D position-sensitive detector by neutron reflection on a double-focusing toroidal mirror. It permits to perform SANS studies with a scattering wave vector resolution between 10-3 and 10-4Å-1 with considerable intensity advantages over pinhole-SANS instruments. To date, KWS-3 is the worldwide unique SANS instrument running on this principle. We present here the characterization of the image produced by the mirror and a measurement of the scattering from a diffraction grating.

  19. Characterization of nanoparticles of lidocaine in w/o microemulsions using small-angle neutron scattering and dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Shukla, A.; Kiselev, M. A.; Hoell, A.; Neubert, R. H. H.

    2004-08-01

    Microemulsions (MEs) are of special interest because a variety of Reactants can be introduced into the nanometer-sized aqueous domains, leading to materials with controlled size and shape [1,2]. In the past few years, significant research has been conducted in the reverse ME-mediated synthesis of organic nanoparticles [3,4]. In this study, a w/o ME medium was employed for the synthesis of lidocaine by direct precipitation in w/o microemulsion systems: water/isopropylpalmitat/Tween80/Span80. The particle size as well as the location of nanoparticles in the ME droplet were characterized by means of dynamic light scattering (DLS) and small angle neutron scattering (SANS). It is observed that lidocaine precipitated in the aqueous cores because of its insolubility in water. Hydrodynamic radius and gyration radius of microemulsion droplets were estimated as ~15 nm and ~4.50 nm from DLS and SANS respectively. Furthermore, different size parameters obtained by DLS and SANS experiments were compared

  20. Internal structures of agar-gelatin co-hydrogels by light scattering, small-angle neutron scattering and rheology.

    PubMed

    Santinath Singh, S; Aswal, V K; Bohidar, H B

    2011-06-01

    Internal structures of agar-gelatin co-hydrogels were investigated as a function of their volumetric mixing ratio, [Formula: see text] , 1.0 and 2.0 using dynamic light scattering (DLS), small-angle neutron scattering (SANS) and rheology. The degree of non-ergodicity ( X = 0.2 ± 0.02) , which was extracted as a heterodyne contribution from the measured dynamic structure factor data remained less than that of homogeneous solutions where ergodicity is expected (X = 10. The static structure factor, I(q) , results obtained from SANS were interpreted in the Guinier regime (low-q , which implied the existence of ≈ 250 nm long rod-like structures (double-helix bundles), and the power law (intermediate-q regions) yielded I (q) ~ q(−α) with α = 2.3 , 1.8 and 1.6 for r = 0.5 , 1.0 and 2.0. This is indicative of the presence of Gaussian chains at low r , while at r = 2 there was a propensity of rod-shaped structures. The gel strength and transition temperatures measured from frequency sweep and temperature ramp studies were suggestive of the presence of a stronger association between the two biopolymer networks at higher r . The results indicate that the internal structures of agar-gelatin co-hydrogels were highly dependent on the volumetric mixing ratio.

  1. Small-angle neutron scattering study of recombinant yeast-derived human hepatitis B virus surface antigen vaccine particle

    NASA Astrophysics Data System (ADS)

    Sato, M.; Ito, Y.; Kameyama, K.; Imai, M.; Ishikawa, N.; Takagi, T.

    1995-02-01

    The overall and internal structure of recombinant yeast-derived human hepatitis B virus surface antigen vaccine particles was investigated by small-angle neutron scattering using the contrast variation method. The vaccine is a nearly spherical particle, and its contrast-matching point was determined to be at about 24% D 2O content, indicating that a large part of the vaccine particle is occupied by lipids and carbohydrates from the yeast. The Stuhrmann plot suggests that the surface antigens exist predominantly in the peripheral region of the particle, which is favorable to the induction of anti-virus antibodies.

  2. Investigation of coercivity mechanism in hot deformed Nd-Fe-B permanent magnets by small-angle neutron scattering

    SciTech Connect

    Yano, M. Manabe, A.; Shoji, T.; Kato, A.; Ono, K.; Harada, M.; Kohlbrecher, J.

    2014-05-07

    The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd{sub 2}Fe{sub 14}B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains.

  3. Morphology of poly(ethylene oxide) dissolved in a room temperature ionic liquid: a small angle neutron scattering study.

    PubMed

    Triolo, Alessandro; Russina, Olga; Keiderling, Uwe; Kohlbrecher, Joachim

    2006-02-02

    Solutions of deuterated poly(ethylene oxide) (d-PEO) in 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]), a prototype room-temperature ionic liquid (RTIL), have been studied at room temperature over a range of polymer concentrations, using small angle neutron scattering (SANS), characterizing the conformation of PEO dissolved in RTILs. [bmim][BF4] behaves as a good solvent for d-PEO, which organizes in this solvent in non entangled random coils. These findings will help in optimizing the designing of microemulsions in these potentially environmentally friendly solvents.

  4. Deformation of poly(methyl methacrylate)-poly(ethylene oxide) blends: a molecular characterization by small-angle neutron scattering

    SciTech Connect

    Lefebvre, J.M.R.; Porter, S.; Wignall, G.D.

    1986-01-01

    The deformation behavior of miscible amorphous/amorphous PMMA/PEO blends has been compared to that of pure PMMA. Small-angle neutron scattering experiments have been performed on labeled systems made of PEO + D-PMMA + H-PMMA. Characteristic molecular parameters such as radius of gyration R/sub g/, molecular weight M/sub w/ and interaction parameter X have been extracted from the coherent scattering cross sections. Molecular anisotropy is measured on the solid state coextruded samples and the observed drawing efficiency is compared to the results of shrinkage tests. In the case of PMMA/PEO blends, anomalous scattering behavior precludes any quantitative interpretation of the scattering patterns, but revealed important structural changes upon drawing, namely a deformation-induced phase separation.

  5. Small angle neutron scattering studies of HbA in concentrated solutions.

    PubMed Central

    Krueger, S; Chen, S H; Hofrichter, J; Nossal, R

    1990-01-01

    Differential cross-sections for neutrons scattered by normal human hemoglobin have been determined over the range of concentrations from 2 to approximately 35 weight percent. Data are compared with structure factors calculated from models of monodisperse hard spheres interacting through a screened Coulomb potential. Good agreement is noted when the volume fraction eta is adjusted during multivariate fitting of data, but the fitted value of eta is always lower than expected from the known Hb concentration of the samples. Calculations of cross-sections for polydisperse scatterers suggest that the samples may contain oligomers of the fundamental tetrameric Hb molecule. PMID:2207261

  6. Cavitation on deterministically nanostructured surfaces in contact with an aqueous phase: a small-angle neutron scattering study.

    PubMed

    Melnichenko, Yuri B; Lavrik, N V; Popov, E; Bahadur, J; He, L; Kravchenko, I I; Smith, G; Pipich, V; Szekely, N K

    2014-08-26

    The structure of deterministically nanopatterned surfaces created using a combination of electron beam lithography and reactive ion etching was evaluated using small-angle neutron scattering (SANS). Samples exhibit 2D neutron scattering patterns that confirm the presence of ordered nanoscale cavities consistent with the targeted morphologies as well as with SEM data analysis. Comparison of SANS intensities obtained from samples in air and in contact with an aqueous phase (pure deuterium oxide, D2O, or a contrast matched mixture of D2O + H2O) reveals formation of stable gaseous nanobubbles trapped inside the cavities. The relative volume of nanobubbles depends strongly on the hydrophobicity of the cavity walls. In the case of hydrophobic surfaces, nanobubbles occupy up to 87% of the total cavity volume. The results demonstrate the high degree of sensitivity of SANS measurements for detecting and characterizing nano- and mesoscale bubbles with the volume fraction as low as ∼10(-6).

  7. The new small-angle neutron scattering instrument SANS-1 at MLZ-characterization and first results

    NASA Astrophysics Data System (ADS)

    Mühlbauer, S.; Heinemann, A.; Wilhelm, A.; Karge, L.; Ostermann, A.; Defendi, I.; Schreyer, A.; Petry, W.; Gilles, R.

    2016-10-01

    A thorough characterization of the key features of the new small-angle neutron scattering instrument SANS-1 at MLZ, a joint project of Technische Universität München and Helmholtz Zentrum Geesthacht, is presented. Measurements of the neutron beam profile, divergency and flux are given for various positions along the instrument including the sample position, and agree well with Monte Carlo simulations of SANS-1 using the program McStas. Secondly, the polarization option of SANS-1 is characterized for a broad wavelength band. A key feature of SANS-1 is the large accessible Q-range facilitated by the sideways movement of the detector. Particular attention is hence paid to the effects that arise due to large scattering angles on the detector where a standard cos3 solid angle correction is no longer applicable. Finally the performance of the instrument is characterized by a set of standard samples.

  8. Concept for a time-of-flight Small Angle Neutron Scattering instrument at the European Spallation Source

    NASA Astrophysics Data System (ADS)

    Jaksch, S.; Martin-Rodriguez, D.; Ostermann, A.; Jestin, J.; Duarte Pinto, S.; Bouwman, W. G.; Uher, J.; Engels, R.; Frielinghaus, H.

    2014-10-01

    A new Small Angle Neutron Scattering instrument is proposed for the European Spallation Source. The pulsed source requires a time-of-flight analysis of the gathered neutrons at the detector. The optimal instrument length is found to be rather large, which allows for a polarizer and a versatile collimation. The polarizer allows for studying magnetic samples and incoherent background subtraction. The wide collimation will host VSANS and SESANS options that increase the resolution of the instrument towards μm and tens of μm, respectively. Two 1 m2 area detectors will cover a large solid angle simultaneously. The expected gains for this new instrument will lie in the range between 20 and 36, depending on the assessment criteria, when compared to up-to-date reactor based instruments. This will open new perspectives for fast kinetics, weakly scattering samples, and multi-dimensional contrast variation studies.

  9. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    DOE PAGES

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; ...

    2015-09-21

    In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach producesmore » robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).« less

  10. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    PubMed Central

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; Katsaras, John

    2015-01-01

    We review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). From model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.). PMID:26402708

  11. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    SciTech Connect

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; Katsaras, John

    2015-09-21

    In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).

  12. Structural and mechanical properties of cardiolipin lipid bilayers determined using neutron spin echo, small angle neutron and X-ray scattering, and molecular dynamics simulations

    DOE PAGES

    Pan, Jianjun; Cheng, Xiaolin; Sharp, Melissa; ...

    2014-10-29

    We report that the detailed structural and mechanical properties of a tetraoleoyl cardiolipin (TOCL) bilayer were determined using neutron spin echo (NSE) spectroscopy, small angle neutron and X-ray scattering (SANS and SAXS, respectively), and molecular dynamics (MD) simulations. We used MD simulations to develop a scattering density profile (SDP) model, which was then utilized to jointly refine SANS and SAXS data. In addition to commonly reported lipid bilayer structural parameters, component distributions were obtained, including the volume probability, electron density and neutron scattering length density.

  13. Structural and mechanical properties of cardiolipin lipid bilayers determined using neutron spin echo, small angle neutron and X-ray scattering, and molecular dynamics simulations

    SciTech Connect

    Pan, Jianjun; Cheng, Xiaolin; Sharp, Melissa; Ho, Chian-Sing; Khadka, Nawal; Katsaras, John

    2014-10-29

    We report that the detailed structural and mechanical properties of a tetraoleoyl cardiolipin (TOCL) bilayer were determined using neutron spin echo (NSE) spectroscopy, small angle neutron and X-ray scattering (SANS and SAXS, respectively), and molecular dynamics (MD) simulations. We used MD simulations to develop a scattering density profile (SDP) model, which was then utilized to jointly refine SANS and SAXS data. In addition to commonly reported lipid bilayer structural parameters, component distributions were obtained, including the volume probability, electron density and neutron scattering length density.

  14. Preparing Monodisperse Macromolecular Samples for Successful Biological Small-Angle X-ray and Neutron Scattering Experiments

    PubMed Central

    Jeffries, Cy M.; Graewert, Melissa A.; Blanchet, Clément E.; Langley, David B.; Whitten, Andrew E.; Svergun, Dmitri I

    2017-01-01

    Small-angle X-ray and neutron scattering (SAXS and SANS) are techniques used to extract structural parameters and determine the overall structures and shapes of biological macromolecules, complexes and assemblies in solution. The scattering intensities measured from a sample contain contributions from all atoms within the illuminated sample volume including the solvent and buffer components as well as the macromolecules of interest. In order to obtain structural information, it is essential to prepare an exactly matched solvent blank so that background scattering contributions can be accurately subtracted from the sample scattering to obtain the net scattering from the macromolecules in the sample. In addition, sample heterogeneity caused by contaminants, aggregates, mismatched solvents, radiation damage or other factors can severely influence and complicate data analysis so it is essential that the samples are pure and monodisperse for the duration of the experiment. This Protocol outlines the basic physics of SAXS and SANS and reveals how the underlying conceptual principles of the techniques ultimately ‘translate’ into practical laboratory guidance for the production of samples of sufficiently high quality for scattering experiments. The procedure describes how to prepare and characterize protein and nucleic acid samples for both SAXS and SANS using gel electrophoresis, size exclusion chromatography and light scattering. Also included are procedures specific to X-rays (in-line size exclusion chromatography SAXS) and neutrons, specifically preparing samples for contrast matching/variation experiments and deuterium labeling of proteins. PMID:27711050

  15. The solution structure of functionally active human proliferating cell nuclear antigen determined by small-angle neutron scattering.

    PubMed

    Schurtenberger, P; Egelhaaf, S U; Hindges, R; Maga, G; Jónsson, Z O; May, R P; Glatter, O; Hübscher, U

    1998-01-09

    The function of proliferating cell nuclear antigen (PCNA) in DNA replication and repair is to form a sliding clamp with replication factor C (RF-C) tethering DNA polymerase delta or epsilon to DNA. In addition, PCNA has been found to interact directly with various proteins involved in cell cycle regulation. The crystal structure of yeast PCNA shows that the protein forms a homotrimeric ring lining a hole through which double-stranded DNA can thread, thus forming a moving platform for DNA synthesis. Human and yeast PCNA are highly conserved at a structural and functional level. We determined the solution structure of functionally active human PCNA by small-angle neutron scattering. Our measurements strongly support a trimeric ring-like structure of functionally active PCNA in solution, and the data are in good agreement with model calculations based on the crystal structure from yeast PCNA. The human PCNA used in the small-angle neutron scattering experiments was active before and after the measurements in a RF-C independent and a RF-C dependent assay suggesting that the trimeric structure is the in vivo functional form.

  16. Anisotropic small angle neutron scattering analysis of thermally aged reactor-vessel materials

    NASA Astrophysics Data System (ADS)

    Rétfalvi, E.; Török, Gy.; Rosta, L.

    Neutron radiation and high working temperatures induce important changes in the microstructure of metallic components of nuclear reactors. These changes result in weakening of the mechanical properties, which is the primary interest in the safety and lifetime management of nuclear installations. In order to follow up the microstructural changes, separately due to radiation and high temperature, first we measured thermally aged steel samples. The observed anisotropic scattering was fitted by a 2D model. We found that the microstructure of aged metals shows a strong dependence on the industrial treatment quality and also on the sampling.

  17. Fractal approach in petrology: Small-angle neutron scattering experiments with volcanic rocks

    SciTech Connect

    Lucido, G.; Triolo, R.; Caponetti, E.

    1988-11-01

    Following Mandelbrot's pioneering work in 1977, we attempt to use the concept of fractal dimension in petrology. Fractal dimension is an intensive property of matter which offers a quantitative measure of the degree of surface roughness. Neutron scattering experiments have been performed on 18 volcanic rocks from different localities. The scattered intensity as a function of the momentum transfer obeys a power law whose exponent varies, for the rock samples presented, between -3 and -4. We conclude that, at the molecular level, our volcanic rocks are not fractal volumes. With regard to the particle-matrix interface, it is not possible to provide a determination at the present stage of research. Our findings suggest it is feasible to verify the degree of surface irregularity at a resolution which is relevant to many aspects of petrology.

  18. Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

    DOE PAGES

    Yan, Y.; Qian, S.; Littrell, K.; ...

    2015-02-13

    A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distributionmore » of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. This study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor will be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.« less

  19. Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

    SciTech Connect

    Yan, Y.; Qian, S.; Littrell, K.; Parish, C. M.; Plummer, L. K.

    2015-02-13

    A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distribution of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. This study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor will be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.

  20. Hierarchical Pore Morphology of Cretaceous Shale: A Small-Angle Neutron Scattering and Ultrasmall-Angle Neutron Scattering Study

    DOE PAGES

    Bahadur, J.; Melnichenko, Y. B.; Mastalerz, Maria; ...

    2014-09-25

    Shale reservoirs are becoming an increasingly important source of oil and natural gas supply and a potential candidate for CO2 sequestration. Understanding the pore morphology in shale may provide clues to making gas extraction more efficient and cost-effective. The porosity of Cretaceous shale samples from Alberta, Canada, collected from different depths with varying mineralogical compositions, has been investigated by small- and ultrasmall-angle neutron scattering. Moreover these samples come from the Second White Specks and Belle Fourche formations, and their organic matter content ranges between 2 and 3%. The scattering length density of the shale specimens has been estimated using themore » chemical composition of the different mineral components. Scattering experiments reveal the presence of fractal and non-fractal pores. It has been shown that the porosity and specific surface area are dominated by the contribution from meso- and micropores. The fraction of closed porosity has been calculated by comparing the porosities estimated by He pycnometry and scattering techniques. There is no correlation between total porosity and mineral components, a strong correlation has been observed between closed porosity and major mineral components in the studied specimens.« less

  1. Hierarchical Pore Morphology of Cretaceous Shale: A Small-Angle Neutron Scattering and Ultrasmall-Angle Neutron Scattering Study

    SciTech Connect

    Bahadur, J.; Melnichenko, Y. B.; Mastalerz, Maria; Furmann, Agnieszka; Clarkson, Chris R.

    2014-09-25

    Shale reservoirs are becoming an increasingly important source of oil and natural gas supply and a potential candidate for CO2 sequestration. Understanding the pore morphology in shale may provide clues to making gas extraction more efficient and cost-effective. The porosity of Cretaceous shale samples from Alberta, Canada, collected from different depths with varying mineralogical compositions, has been investigated by small- and ultrasmall-angle neutron scattering. Moreover these samples come from the Second White Specks and Belle Fourche formations, and their organic matter content ranges between 2 and 3%. The scattering length density of the shale specimens has been estimated using the chemical composition of the different mineral components. Scattering experiments reveal the presence of fractal and non-fractal pores. It has been shown that the porosity and specific surface area are dominated by the contribution from meso- and micropores. The fraction of closed porosity has been calculated by comparing the porosities estimated by He pycnometry and scattering techniques. There is no correlation between total porosity and mineral components, a strong correlation has been observed between closed porosity and major mineral components in the studied specimens.

  2. Vacuum System Upgrade for Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS) at SNS

    SciTech Connect

    Stone, Christopher M.; Williams, Derrick C.; Price, Jeremy P.

    2016-09-23

    The Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS) instrument at the Spallation Neutron Source (SNS), Oak Ridge, Tennessee, incorporates a 69m3 detector vessel with a vacuum system which required an upgrade with respect to performance, ease of operation, and maintenance. The upgrade focused on improving pumping performance as well as optimizing system design to minimize opportunity for operational error. This upgrade provided the following practical contributions: Reduced time required to evacuate from atmospheric pressure to 2mTorr from 500-1,000 minutes to 60-70 minutes Provided turn-key automated control with a multi-faceted interlock for personnel and machine safety.

  3. Design and use of a double crystal diffractometer for very small angle neutron scattering at JRR-3M

    NASA Astrophysics Data System (ADS)

    Aizawa, K.; Tomimitsu, H.

    1995-02-01

    The double crystal diffractometer (DCD) for very small angle neutron scattering (VSANS) in the precise neutron optics (PNO) apparatus on a 3G beam hole at JRR-3M is described. The DCD consists of a nondispersive (1, - 1) setting of 111 reflection of silicon single crystals with a sample between two crystals and is set on a vibration isolator table in a constant temperature chamber. The peak intensity of a rocking curve without a sample is 2200 cps at a detector position and the signal to noise ratio is 1.6 × 10 4 in a typical experiment. VSANS measurements for silica powder samples reveal that the q-range is available between 2 × 10 -4 and 6 × 10 -2 nm -1.

  4. Preliminary experiments on apparatus for in situ studies of microwave-driven reactions by small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Whittaker, A. G.; Harrison, A.; Oakley, G. S.; Youngson, I. D.; Heenan, R. K.; King, S. M.

    2001-01-01

    In this article we describe apparatus for the study of the microwave-driven growth of particles in solution by in situ small angle neutron scattering (SANS). This apparatus has enabled the first preliminary experiments using microwave-activated in situ diffraction. We take iron oxide as the prototype system, but the technique may be extended to a wide variety of chemical reactions that deposit solids from solution. The key features of the apparatus are a microwave cavity with a modular construction that may be adapted to the geometric constraints of the diffractometer, and a computer-controlled microwave generator that may be set to maintain either constant pressure or temperature in the reaction vessel. In this particular piece of equipment the reaction vessel is adapted so that part of the sample fills a cell of identical construction to those commonly used in SANS measurements for optimal transmission of the neutron beam.

  5. X-ray magnetic circular dichroism and small angle neutron scattering study of thiol capped gold nanoparticles.

    SciTech Connect

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; Pinel, E. F.; te Velthuis, S. G. E.; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian, C.; Garcia, M. A.; Univ. Complutense de Madrid; Inst. de Magnetismo Aplicado UCM; Univ. Pisa; Univ. di Padova

    2009-11-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  6. X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles.

    PubMed

    de la Venta, J; Bouzas, V; Pucci, A; Laguna-Marco, M A; Haskel, D; te Velthuis, S G E; Hoffmann, A; Lal, J; Bleuel, M; Ruggeri, G; de Julián Fernández, C; García, M A

    2009-11-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 x 10(-4) was found at the Au L3 edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M(S), of 0.06 emu/g(Au). SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  7. Vacuum System Upgrade for Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS) at SNS

    DOE PAGES

    Stone, Christopher M.; Williams, Derrick C.; Price, Jeremy P.

    2016-09-23

    The Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS) instrument at the Spallation Neutron Source (SNS), Oak Ridge, Tennessee, incorporates a 69m3 detector vessel with a vacuum system which required an upgrade with respect to performance, ease of operation, and maintenance. The upgrade focused on improving pumping performance as well as optimizing system design to minimize opportunity for operational error. This upgrade provided the following practical contributions: Reduced time required to evacuate from atmospheric pressure to 2mTorr from 500-1,000 minutes to 60-70 minutes Provided turn-key automated control with a multi-faceted interlock for personnel and machine safety.

  8. Small-Angle Scattering on Magnetoferritin Nanoparticles

    NASA Astrophysics Data System (ADS)

    Balejčíková Petrenko, L., VI; Avdeev, MV; Garamus, VM; Almásy, L.; Kopčanský, P.

    2017-05-01

    Magnetoferritin is a synthetically prepared magnetic bio-complex, consisting of apoferritin shell and iron-based nanoparticles. Superparamagnetic behaviour, nanoscale size (about 12 nm) and biological origin allow to use magnetoferritin in various applications. In this report, we present a general overview about basic physicochemical properties of magnetoferritin, as determined by small-angle X-ray and neutron scattering experiments and some interesting references on their potential bio-applications.

  9. The study of the structural properties of very low viscosity sodium alginate by small-angle neutron scattering

    SciTech Connect

    Badita, C. R.; Aranghel, D.; Radulescu, A.; Anitas, E. M.

    2016-03-25

    Sodium alginate is a linear polymer extract from brown algae and it is used in the biomedical, food, cosmetics and pharmaceutical industries as solution property modifiers and gelling agents. But despite the extensive studies of the alginate gelation process, still some fundamental questions remain unresolved. The fractal behavior of very low viscosity sodium alginate solutions and their influence on the critical gelation of alginate induced by Ca{sup 2+} ions were investigated using Small-Angle Neutron Scattering (SANS) measurements. SANS data are interpreted using both standard linear plots and the Beaucage model. The scattering intensity is dependent by alginate concentration and Ca{sup 2+} concentration. From a critical concentration of 1.0 % w/w our polymer swelled forming spherical structures with rough surfaces. Also the addition of the salt induces the collapse and the appearance of the aggregation and clusters formation.

  10. The study of the structural properties of very low viscosity sodium alginate by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Badita, C. R.; Aranghel, D.; Radulescu, A.; Anitas, E. M.

    2016-03-01

    Sodium alginate is a linear polymer extract from brown algae and it is used in the biomedical, food, cosmetics and pharmaceutical industries as solution property modifiers and gelling agents. But despite the extensive studies of the alginate gelation process, still some fundamental questions remain unresolved. The fractal behavior of very low viscosity sodium alginate solutions and their influence on the critical gelation of alginate induced by Ca2+ ions were investigated using Small-Angle Neutron Scattering (SANS) measurements. SANS data are interpreted using both standard linear plots and the Beaucage model. The scattering intensity is dependent by alginate concentration and Ca2+ concentration. From a critical concentration of 1.0 % w/w our polymer swelled forming spherical structures with rough surfaces. Also the addition of the salt induces the collapse and the appearance of the aggregation and clusters formation.

  11. Micro-focused Small Angle Neutron Scattering and Imaging for Science and Engineering Using RTP--A Preliminary Study

    SciTech Connect

    Mohamed, Abdul Aziz; Al Rashid Megat Ahmad, Megat Harun; Md Idris, Faridah; Azman, Azraf; Jamro, Rafhayudi; Ibrahim, Mohd Rizal Mamat; Rahman, Anwar Abdul

    2010-01-05

    Malaysian Nuclear Agency's (Nuclear Malaysia) Small Angle Neutron Scattering (SANS) facility--(MYSANS)--is utilizing low flux of thermal neutron at the agency's 1 MW TRIGA reactor. As the design nature of the 8 m SANS facility can allow object resolution in the range between 5 and 80 nm to be obtained. It can be used to study alloys, ceramics and polymers in certain area of problems that relate to samples containing strong scatterers or contrast. The current SANS system at Malaysian Nuclear Agency is only capable to measure Q in limited range with a PSD (128x128) fixed at 4 m from the sample. The existing reactor hall that incorporate this MYSANS facility has a layout that prohibits the rebuilding of MYSANS therefore the position between the wavelength selector (HOPG) and sample and the PSD cannot be increased for wider Q range. The flux of the neutron at current sample holder is very low which around 10{sup 3} n/cm{sup 2}/sec. Thus it is important to rebuild the MYSANS to maximize the utilization of neutron. Over the years, the facility has undergone maintenance and some changes have been made. Modification on secondary shutter and control has been carried out to improve the safety level of the instrument. A compact micro-focus SANS method can suit this objective together with an improve cryostat system. This paper will explain some design concept and approaches in achieving higher flux and the modification needs to establish the micro-focused SANS.

  12. Hierarchical architecture of bacterial cellulose and composite plant cell wall polysaccharide hydrogels using small angle neutron scattering.

    PubMed

    Martínez-Sanz, Marta; Gidley, Michael J; Gilbert, Elliot P

    2016-02-07

    Small angle neutron scattering (SANS) has been applied to characterise the structure of pure bacterial cellulose hydrogels, and composites thereof, with two plant cell wall polysaccharides (arabinoxylan and xyloglucan). Conventional published models, which assume that bacterial cellulose ribbons are solid one-phase systems, fail to adequately describe the SANS data of pure bacterial cellulose. Fitting of the neutron scattering profiles instead suggests that the sub-structure of cellulose microfibrils contained within the ribbons results in the creation of regions with distinct values of neutron scattering length density, when the hydrogels are subjected to H2O/D2O exchange. This may be represented within a core-shell formalism that considers the cellulose ribbons to comprise a core containing impermeable crystallites surrounded by a network of paracrystalline cellulose and tightly bound water, and a shell containing only paracrystalline cellulose and water. Accordingly, a fitting function comprising the sum of a power-law term to account for the large scale structure of intertwined ribbons, plus a core-shell cylinder with polydisperse radius, has been applied; it is demonstrated to simultaneously describe all SANS contrast variation data of pure and composite bacterial cellulose hydrogels. In addition, the resultant fitting parameters indicate distinct interaction mechanisms of arabinoxylan and xyloglucan with cellulose, revealing the potential of this approach to investigate the role of different plant cell wall polysaccharides on the biosynthesis process of cellulose.

  13. Anomalous and resonance small angle scattering: Revision

    SciTech Connect

    Epperson, J.E.; Thiyagarajan, P.

    1987-11-01

    Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same for the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small angle neutron scatterings are discussed. 54 refs., 8 figs., 1 tab.

  14. Anomalous and resonance small angle scattering

    SciTech Connect

    Epperson, J.E.; Thiyagarajan, P.

    1987-11-01

    Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same or the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scatterings are discussed. 8 figs.

  15. Characterization of oligomerization of a peptide from the ebola virus glycoprotein by small-angle neutron scattering

    SciTech Connect

    Egorov, V. V.; Gorshkov, A. N.; Murugova, T. N.; Vasin, A. V.; Lebedev, D. V.; Isaev-Ivanov, V. V.; Kiselev, O. I.

    2016-01-15

    Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) studies showed that model peptides QNALVCGLRQ (G33) and QNALVCGLRG (G31) corresponding to region 551–560 of the GP protein of the Sudan Ebola virus are prone to oligomerization in solution. Both peptides can form amyloid-like fibrills. The G33 peptide forms fibrils within one day of incubation, whereas the fibrillogenesis of the G31 peptide is observed only after incubation for several months. The possible role of the observed processes in the pathogenesis and the possibility of applying a combination of the TEM and SANS techniques to search for new compounds that are able to influence the protein oligomerization are discussed.

  16. Characterization of oligomerization of a peptide from the ebola virus glycoprotein by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Egorov, V. V.; Gorshkov, A. N.; Murugova, T. N.; Vasin, A. V.; Lebedev, D. V.; Isaev-Ivanov, V. V.; Kiselev, O. I.

    2016-01-01

    Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) studies showed that model peptides QNALVCGLRQ (G33) and QNALVCGLRG (G31) corresponding to region 551-560 of the GP protein of the Sudan Ebola virus are prone to oligomerization in solution. Both peptides can form amyloid-like fibrills. The G33 peptide forms fibrils within one day of incubation, whereas the fibrillogenesis of the G31 peptide is observed only after incubation for several months. The possible role of the observed processes in the pathogenesis and the possibility of applying a combination of the TEM and SANS techniques to search for new compounds that are able to influence the protein oligomerization are discussed.

  17. Analysis of the pore structure of activated carbons produced from paper mill sludge using small angle neutron scattering data

    SciTech Connect

    Sandi, G.; Khalil, N. R.; Littrell, K.; Thiyagarajan, P.

    1999-12-13

    A novel, cost-effective, and environmentally benign process was developed to produce highly efficient carbon-based adsorbents (CBAs) from paper mill sludge. The production process required chemical activation of sludge using zinc chloride and pyrolysis at 750 C in N{sub 2} gas. The produced CBAs were characterized according to their surface area and pore size distribution using N{sub 2}-BET adsorption isotherm data. Further characterization of the surface and pore structure was conducted using a unified exponential/power law approach applied to small angle neutron scattering (SANS) data. The structural features analyzed by SANS revealed the dependence of porosity with zinc chloride concentration. The presence of inaccessible pores was also determined by contrast-match experiments.

  18. Spin-echo small-angle neutron scattering study of the structure organization of the chromatin in biological cell

    NASA Astrophysics Data System (ADS)

    Iashina, E. G.; Bouwman, W. G.; Duif, C. P.; Filatov, M. V.; Grigoriev, S. V.

    2017-06-01

    Spin-echo small-angle scattering (SESANS) technique is a method to measure the structure of materials from nano- to micrmeter length scales. This method could be important for studying the packaging of DNA in the eukaryotic cell. We measured the SESANS function from chicken erythrocyte nuclei which is well fitted by the exponential function G(z) = exp(-z/ξ), where ξ is the correlation length of a nucleus (in experimental data ξ = 3, 3 μm). The exponential decay of G(z) corresponds to the logarithmic pair correlation function γ(r) = ln(ξ/r). As the sensitivity of the SESANS signal depends on the neutron wavelength, we propose the SESANS setup with the changeable wavelength in the range from 2 to 12 Å. Such option allows one to study in great detail the internal structure of the biological cell in the length scale from 10-2 μm to 10 μm.

  19. Small-angle neutron scattering by the tungsten and molybdenum oxides synthesized from polymer-salt complexes in acidic medium

    NASA Astrophysics Data System (ADS)

    Bogdanov, S.; Valiev, E.; Pirogov, A.; Teplykh, A.; Ostroushko, A.

    2004-07-01

    The peculiarities of oxide phase formation processes under the pyrolysis of salt and polymer-salt compounds based on polyvinyl alcohol and molybdenum and tungsten salts acidified by nitric acid have been studied. For that samples were prepared by annealing in a temperature range of 100-600°C and investigated by small-angle neutron scattering and X-ray diffraction methods. Similar samples with no polymer in their composition were studied for comparison. A size distribution of oxide phase particles, a specific surface area, a volume fraction and a mean particle size were found to be dependent on an annealing temperature and availability of the polymer. The characteristics of the above samples were compared with those of the earlier samples synthesized from solutions with a naturally established acidity. A mechanism of oxide particle formation under a thermal decomposition of the acidic compounds is provided.

  20. Morphology of crystalline-amorphous olefin block copolymers in solution characterized by small-angle neutron scattering and microscopy.

    PubMed

    Radulescu, Aurel; Goerigk, Günter; Fetters, Lewis; Richter, Dieter

    2015-12-01

    The single-chain properties and self-assembly behavior in dilute solution of olefin block copolymers obtained by chain-shuttling technology and consisting of alternating crystallizable and amorphous ethylene/1-octene blocks were investigated by pinhole and focusing small-angle neutron scattering techniques, optical microscopy in bright-field and crossed-polarizer modes, and differential scanning calorimetry. The complex hydrocarbon soluble (precipitant free) macro-aggregates formed with decreasing temperature are characterized by spherulitic textures. The spherulites yield, on one hand, a morphology that depends on the chain structure properties and, on the other hand, multiple structural levels with a hierarchical organization that ranges from 10 Å up to tens of micrometres. This morphology displays peculiarities dictated by the polydisperse character of these materials.

  1. Morphology of crystalline–amorphous olefin block copolymers in solution characterized by small-angle neutron scattering and microscopy

    PubMed Central

    Radulescu, Aurel; Goerigk, Günter; Fetters, Lewis; Richter, Dieter

    2015-01-01

    The single-chain properties and self-assembly behavior in dilute solution of olefin block copolymers obtained by chain-shuttling technology and consisting of alternating crystallizable and amorphous ethylene/1-octene blocks were investigated by pinhole and focusing small-angle neutron scattering techniques, optical microscopy in bright-field and crossed-polarizer modes, and differential scanning calorimetry. The complex hydrocarbon soluble (precipitant free) macro-aggregates formed with decreasing temperature are characterized by spherulitic textures. The spherulites yield, on one hand, a morphology that depends on the chain structure properties and, on the other hand, multiple structural levels with a hierarchical organization that ranges from 10 Å up to tens of micrometres. This morphology displays peculiarities dictated by the polydisperse character of these materials. PMID:26664344

  2. Segmental, Domain-Selective Perdeuteration and Small-Angle Neutron Scattering for Structural Analysis of Multi-Domain Proteins.

    PubMed

    Sonntag, Miriam; Jagtap, Pravin Kumar Ankush; Simon, Bernd; Appavou, Marie-Sousai; Geerlof, Arie; Stehle, Ralf; Gabel, Frank; Hennig, Janosch; Sattler, Michael

    2017-08-01

    Multi-domain proteins play critical roles in fine-tuning essential processes in cellular signaling and gene regulation. Typically, multiple globular domains that are connected by flexible linkers undergo dynamic rearrangements upon binding to protein, DNA or RNA ligands. RNA binding proteins (RBPs) represent an important class of multi-domain proteins, which regulate gene expression by recognizing linear or structured RNA sequence motifs. Here, we employ segmental perdeuteration of the three RNA recognition motif (RRM) domains in the RBP TIA-1 using Sortase A mediated protein ligation. We show that domain-selective perdeuteration combined with contrast-matched small-angle neutron scattering (SANS), SAXS and computational modeling provides valuable information to precisely define relative domain arrangements. The approach is generally applicable to study conformational arrangements of individual domains in multi-domain proteins and changes induced by ligand binding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Octamer formation in lysozyme solutions at the initial crystallization stage detected by small-angle neutron scattering.

    PubMed

    Boikova, Anastasiia S; Dyakova, Yulia A; Ilina, Kseniia B; Konarev, Petr V; Kryukova, Alyona E; Kuklin, Alexandr I; Marchenkova, Margarita A; Nabatov, Boris V; Blagov, Alexandr E; Pisarevsky, Yurii V; Kovalchuk, Mikhail V

    2017-07-01

    Solutions of lysozyme in heavy water were studied by small-angle neutron scattering (SANS) at concentrations of 40, 20 and 10 mg ml(-1) with and without the addition of precipitant, and at temperatures of 10, 20 and 30°C. In addition to the expected protein monomers, dimeric and octameric species were identified in solutions at the maximum concentration and close to the optimal conditions for crystallization. An optimal temperature for octamer formation was identified and both deviation from this temperature and a reduction in protein concentration led to a significant decrease in the volume fractions of octamers detected. In the absence of precipitant, only monomers and a minor fraction of dimers are present in solution.

  4. Effect of surfactant excess on the stability of low-polarity ferrofluids probed by small-angle neutron scattering

    SciTech Connect

    Petrenko, V. I. Avdeev, M. V.; Bulavin, L. A.; Almasy, L.; Grigoryeva, N. A.; Aksenov, V. L.

    2016-01-15

    The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and ?12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of acid to an initially stable system with optimal composition leads to more significant structural changes (related to aggregation) than those observed previously for this class of FFs. A comparison of the influence of monocarboxylic acids on the stability of nonpolar FFs suggests that the enhancement of aggregation is much more pronounced in the case of palmitic acid excess. This fact confirms the conclusion of previous studies, according to which an increase in the hydrocarbon chain length in a saturated acid reduces the efficiency of the corresponding FF stabilization.

  5. Electron microscopy and small angle neutron scattering study of precipitation in low alloy steel submerged-arc welds

    SciTech Connect

    Williams, T.J.; Phythian, W.J.

    1996-12-31

    In previous studies, submerged-arc welds with a range of compositions were irradiated in test reactors over a range of dose and dose-rates. The effect of irradiation was measured by Charpy V-notch and hardness tests, and an irradiation response model was developed. In this paper the authors report the results of a combined electron microscopy and small angle neutron scattering (SANS) study on material from some of the Charpy specimens. The results have been interpreted in terms of the Russell and Brown modulus hardening model. In general they have confirmed the predictions of the irradiation response model, and shown that the copper precipitation contribution to the observed macroscopic to the observed macroscopic hardening is strongly dependent on nickel, dose and dose-rate.

  6. Exploring the structure of biological macromolecules in solution using Quokka, the small angle neutron scattering instrument, at ANSTO

    NASA Astrophysics Data System (ADS)

    Wood, Kathleen; Jeffries, Cy M.; Knott, Robert B.; Sokolova, Anna; Jacques, David A.; Duff, Anthony P.

    2015-10-01

    Small angle neutron scattering (SANS) is widely used to extract structural parameters, shape and other types of information from a vast array of materials. The technique is applied to biological macromolecules and their complexes in solution to reveal information often not accessible by other techniques. SANS measurements on biomolecules present some particular challenges however, one of which is suitable instrumentation. This review details SANS experiments performed on two well-characterised globular proteins (lysozyme and glucose isomerase) using Quokka, the recently commissioned SANS instrument at the Australian Nuclear Science and Technology Organisation (ANSTO). The instrument configuration as well as data collection and reduction strategies for biological investigations are discussed and act as a general reference for structural biologists who use the instrument. Both model independent analysis of the two proteins and ab initio modelling illustrate that Quokka-SANS data can be used to successfully model the overall shapes of proteins in solution, providing a benchmark for users.

  7. Comparison of the Behavior of Polymers in Supercritical Fluids and Organic Solvents Via Small Angle Neutron Scattering

    SciTech Connect

    Melnichenko, Y.B.; Kiran, E.; Heath, K.D.; Salaniwal, S.; Cochran, H.D.; Stamm, M.; Van Hook, W.A.; Wignall, G.D.

    1999-05-17

    Small-angle neutron scattering has been used to study the effect of temperature and pressure on the phase behavior of semidilute solutions of polymers dissolved in organic and supercritical solvents. Above the theta temperature (To), these systems exhibit a ''good solvent'' domain, where the molecules expand beyond the unperturbed dimensions in both organic solvents and in COZ. However, this transition can be made to occur at a critical ''theta pressure'' (PO) in CO2 and this represents a new concept in the physics of polymer-solvent systems. For T < To, and P < Po, the system enters the ''poor solvent'' domain where diverging concentration fluctuations prevent the chains from collapsing and allow them to maintain their unperturbed dimensions.

  8. Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field

    SciTech Connect

    Klokkenburg, M.; Erne, B. H.; Petukhov, A. V.; Philipse, A. P.; Wiedenmann, A.

    2007-05-15

    Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering (SANS) as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the well-defined, single-magnetic-domain magnetite (Fe{sub 3}O{sub 4}) particles and by applying an external magnetic field. For decreasing particle dipole moments, the data show a progressive distortion of the hexagonal symmetry, resulting from the formation of magnetic sheets. The SANS data show qualitative agreement with recent cryogenic transmission electron microscopy results obtained in 2D [Klokkenburg et al., Phys. Rev. Lett. 97, 185702 (2006)] on the same ferrofluids.

  9. Effect of surfactant excess on the stability of low-polarity ferrofluids probed by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Petrenko, V. I.; Avdeev, M. V.; Bulavin, L. A.; Almasy, L.; Grigoryeva, N. A.; Aksenov, V. L.

    2016-01-01

    The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and ?12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of acid to an initially stable system with optimal composition leads to more significant structural changes (related to aggregation) than those observed previously for this class of FFs. A comparison of the influence of monocarboxylic acids on the stability of nonpolar FFs suggests that the enhancement of aggregation is much more pronounced in the case of palmitic acid excess. This fact confirms the conclusion of previous studies, according to which an increase in the hydrocarbon chain length in a saturated acid reduces the efficiency of the corresponding FF stabilization.

  10. Effect of crystal shape on neutron rocking curves of perfect single crystals designed for ultra-small-angle scattering experiments

    NASA Astrophysics Data System (ADS)

    Freund, A. K.; Rehm, C.

    2014-07-01

    The present study has been conducted in the framework of the channel-cut crystal design for the Kookaburra ultra-small-angle neutron scattering (USANS) instrument to be installed at the OPAL reactor of ANSTO. This facility is based on the classical Bonse-Hart method that uses two multiple-reflection crystal systems. The dynamical theory of diffraction by perfect crystals distinguishes two cases: the Darwin case applying to infinitely thick crystals and the Ewald solution for very small absorption taking into account the reflection from the rear face of a plane-parallel crystal reflecting in Bragg geometry. The former is preferable because it yields narrower rocking curves. To prevent the neutrons to "see" the rear face, grooves were machined into the backside of perfect Si test crystals for single reflection and filled with neutron absorbing material. These samples were examined at the S18 instrument of the Institut Laue-Langevin. Unexpectedly the crystals with empty slots showed an increase of the rocking curve width. When filling the slots with an absorber the widths decreased, but without reaching that of the Darwin curve. Understanding the results and achieving a successful crystal design call for the development of a theory that permits to describe neutron diffraction from crystals with a structured back face.

  11. Small-angle neutron scattering reveals the assembly mode and oligomeric architecture of TET, a large, dodecameric aminopeptidase

    SciTech Connect

    Appolaire, Alexandre; Girard, Eric; Colombo, Matteo; Durá, M. Asunción; Moulin, Martine; Härtlein, Michael; Franzetti, Bruno; Gabel, Frank

    2014-11-01

    The present work illustrates that small-angle neutron scattering, deuteration and contrast variation, combined with in vitro particle reconstruction, constitutes a very efficient approach to determine subunit architectures in large, symmetric protein complexes. In the case of the 468 kDa heterododecameric TET peptidase machine, it was demonstrated that the assembly of the 12 subunits is a highly controlled process and represents a way to optimize the catalytic efficiency of the enzyme. The specific self-association of proteins into oligomeric complexes is a common phenomenon in biological systems to optimize and regulate their function. However, de novo structure determination of these important complexes is often very challenging for atomic-resolution techniques. Furthermore, in the case of homo-oligomeric complexes, or complexes with very similar building blocks, the respective positions of subunits and their assembly pathways are difficult to determine using many structural biology techniques. Here, an elegant and powerful approach based on small-angle neutron scattering is applied, in combination with deuterium labelling and contrast variation, to elucidate the oligomeric organization of the quaternary structure and the assembly pathways of 468 kDa, hetero-oligomeric and symmetric Pyrococcus horikoshii TET2–TET3 aminopeptidase complexes. The results reveal that the topology of the PhTET2 and PhTET3 dimeric building blocks within the complexes is not casual but rather suggests that their quaternary arrangement optimizes the catalytic efficiency towards peptide substrates. This approach bears important potential for the determination of quaternary structures and assembly pathways of large oligomeric and symmetric complexes in biological systems.

  12. Small-angle neutron scattering study of the decomposition of Fe-28Cr-10. 5Co. [none

    SciTech Connect

    Spooner, S.

    1984-01-01

    Dynamic scaling of the decomposition of an Fe-28Cr-10.5Co alloy treated at 450/sup 0/, 500/sup 0/, and 550/sup 0/C after a water quench from 950/sup 0/C was investigated with small-angle neutron scattering. Scattering curves measured from the alloy treated at 500/sup 0/C and 550/sup 0/C for times up to 100 hours can be superimposed on a common curve using a k/sub m/-/sup 1/-scaling of the scattering vector length (k = 4..pi..sin(theta)/lambda) and k/sup 3//sub m/-scaling of the scattering intensity scale, where k/sub m/ is the scattering vector for maximum intensity for each scattering curve. At 450/sup 0/C, however, such dynamic scaling does not apply for treatment times between 32 and 192 hours. The 450/sup 0/C curve for 256 hours does scale to the common curve for treatments at 500/sup 0/C and 550/sup 0/C. The departure from scaling found at 450/sup 0/C is consistent with the absence of sharp interfaces and the persistence of localized clustering or critical scattering in the chromium-rich and iron-rich regions. An analysis of the shape of the scattering curves was made in terms of a cluster interference function. It was found that a Gaussian single cluster function is modulated by a cluster interference function given by (k/k*)/sup n/ exponent n is approximately 4 and k* is the limit in k beyond which the interference function is unity. This exponent is larger than that found in computer simulations and in experimental studies of spinodal systems.

  13. Minimal effects of macromolecular crowding on an intrinsically disordered protein: a small-angle neutron scattering study.

    PubMed

    Goldenberg, David P; Argyle, Brian

    2014-02-18

    Small-angle neutron scattering was used to study the effects of macromolecular crowding by two globular proteins, i.e., bovine pancreatic trypsin inhibitor and equine metmyoglobin, on the conformational ensemble of an intrinsically disordered protein, the N protein of bacteriophage λ. The λ N protein was uniformly labeled with (2)H, and the concentrations of D2O in the samples were adjusted to match the neutron scattering contrast of the unlabeled crowding proteins, thereby masking their contribution to the scattering profiles. Scattering from the deuterated λ N was recorded for samples containing up to 0.12 g/mL bovine pancreatic trypsin inhibitor or 0.2 g/mL metmyoglobin. The radius of gyration of the uncrowded protein was estimated to be 30 Å and was found to be remarkably insensitive to the presence of crowders, varying by <2 Å for the highest crowder concentrations. The scattering profiles were also used to estimate the fractal dimension of λ N, which was found to be ∼1.8 in the absence or presence of crowders, indicative of a well-solvated and expanded random coil under all of the conditions examined. These results are contrary to the predictions of theoretical treatments and previous experimental studies demonstrating compaction of unfolded proteins by crowding with polymers such as dextran and Ficoll. A computational simulation suggests that some previous treatments may have overestimated the effective volumes of disordered proteins and the variation of these volumes within an ensemble. The apparent insensitivity of λ N to crowding may also be due in part to weak attractive interactions with the crowding proteins, which may compensate for the effects of steric exclusion.

  14. Properties of surfactant films in water-in-CO2 microemulsions obtained by small-angle neutron scattering.

    PubMed

    Yan, Ci; Sagisaka, Masanobu; James, Craig; Rogers, Sarah; Alexander, Shirin; Eastoe, Julian

    2014-12-01

    The formation, stability and structural properties of normal liquid phase microemulsions, stabilized by hydrocarbon surfactants, comprising water and hydrocarbon oils can be interpreted in terms of the film bending rigidity (energy) model. Here, this model is tested for unusual water-in-CO2 (w/c) microemulsions, formed at high pressure with supercritical CO2 (sc-CO2) as a solvent and fluorinated surfactants as stabilizers. Hence, it is possible to explore the generality of this model for other types of microemulsions. High Pressure Small-Angle Neutron Scattering (HP-SANS) has been used to study w/c microemulsions, using contrast variation to highlight scattering from the stabilizing fluorinated surfactant films: these data show clear evidence for spherical core-shell structures for the microemulsion droplets. The results extend understanding of w/c microemulsions since previous SANS studies are based only on scattering from water core droplets. Here, detailed structural parameters for the surfactant films, such as thickness and film bending energy, have been extracted from the core-shell SANS profiles revealed by controlled contrast variation. Furthermore, at reduced CO2 densities (∼0.7gcm(-3)), elongated cylindrical droplet structures have been observed, which are uncommon for CO2 microemulsions/emulsions. The implications of the presence of cylindrical micelles and droplets for applications of CO2, and viscosity enhancements are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Explaining the Non-Newtonian Character of Aggregating Monoclonal Antibody Solutions Using Small-Angle Neutron Scattering

    PubMed Central

    Castellanos, Maria Monica; Pathak, Jai A.; Leach, William; Bishop, Steven M.; Colby, Ralph H.

    2014-01-01

    A monoclonal antibody solution displays an increase in low shear rate viscosity upon aggregation after prolonged incubation at 40°C. The morphology and interactions leading to the formation of the aggregates responsible for this non-Newtonian character are resolved using small-angle neutron scattering. Our data show a weak repulsive barrier before proteins aggregate reversibly, unless a favorable contact with high binding energy occurs. Two types of aggregates were identified after incubation at 40°C: oligomers with radius of gyration ∼10 nm and fractal submicrometer particles formed by a slow reaction-limited aggregation process, consistent with monomers colliding many times before finding a favorable strong interaction site. Before incubation, these antibody solutions are Newtonian liquids with no increase in low shear rate viscosity and no upturn in scattering at low wavevector, whereas aggregated solutions under the same conditions have both of these features. These results demonstrate that fractal submicrometer particles are responsible for the increase in low shear rate viscosity and low wavevector upturn in scattered intensity of aggregated antibody solutions; both are removed from aggregated samples by filtering. PMID:25028888

  16. Small Angle X-ray and Neutron Scattering: Powerful Tools for Studying the Structure of Drug-Loaded Liposomes

    PubMed Central

    Di Cola, Emanuela; Grillo, Isabelle; Ristori, Sandra

    2016-01-01

    Nanovectors, such as liposomes, micelles and lipid nanoparticles, are recognized as efficient platforms for delivering therapeutic agents, especially those with low solubility in water. Besides being safe and non-toxic, drug carriers with improved performance should meet the requirements of (i) appropriate size and shape and (ii) cargo upload/release with unmodified properties. Structural issues are of primary importance to control the mechanism of action of loaded vectors. Overall properties, such as mean diameter and surface charge, can be obtained using bench instruments (Dynamic Light Scattering and Zeta potential). However, techniques with higher space and time resolution are needed for in-depth structural characterization. Small-angle X-ray (SAXS) and neutron (SANS) scattering techniques provide information at the nanoscale and have therefore been largely used to investigate nanovectors loaded with drugs or other biologically relevant molecules. Here we revise recent applications of these complementary scattering techniques in the field of drug delivery in pharmaceutics and medicine with a focus to liposomal carriers. In particular, we highlight those aspects that can be more commonly accessed by the interested users. PMID:27043614

  17. SMALL-ANGLE NEUTRON SCATTERING CHARACTERIZATION OF THE STRUCTURE OF NANOPOROUS CARBONS FOR ENERGY-RELATED APPLICATIONS

    SciTech Connect

    He, Lilin; Mavila Chathoth, Suresh; Melnichenko, Yuri B; Presser, Volker; Mcdonough, John; Gogotsi, Yury G.

    2011-01-01

    We used small-angle neutron scattering (SANS) and neutron contrast variation to study the structure of four nanoporouscarbons prepared by thermo-chemical etching of titanium carbide TiC in chlorine at 300, 400, 600, and 800 C with pore diameters ranging between -4 and -11 {angstrom}. SANS patterns were obtained from dry samples and samples saturated with deuterium oxide (D{sub 2}O) in order to delineate origin of the power law scattering in the low Q domain as well as to evaluate pore accessibility for D{sub 2}O molecules. SANS cross section of all samples was fitted to Debye-Anderson-Brumberger (DAB), DAB-Kirste-Porod models as well as to the Guinier and modified Guinier formulae for cylindrical objects, which allowed for evaluating the radii of gyration as well as the radii and lengths of the pores under cylindrical shape approximation. SANS data from D{sub 2}O-saturated samples indicate that strong upturn in the low Q limit usually observed in the scattering patterns from microporous carbon powders is due to the scattering from outer surface of the powder particles. Micropores are only partially filled with D{sub 2}O molecules due to geometrical constraints and or partial hydrophobicity of the carbon matrix. Structural parameters of the dry carbons obtained using SANS are compared with the results of the gas sorption measurements and the values agree for carbide-derived carbons (CDCs) obtained at high chlorination temperatures (>600 C). For lower chlorination temperatures, pore radii obtained from gas sorption overestimate the actual pore size as calculated from SANS for two reasons: inaccessible small pores are present and the model-dependent fitting based on density functional theory models assumes non-spherical pores, whereas SANS clearly indicates that the pore shape in microporous CDC obtained at low chlorination temperatures is nearly spherical.

  18. The effect of pressure, isotopic (H/D) substitution, and other variables on miscibility in polymer-solvent systems. The nature of the demixing process; dynamic light scattering and small angle neutron scattering studies. Final report

    SciTech Connect

    Van Hook, W.A.

    2000-01-01

    A research program examining the effects of pressure, isotope substitution and other variables on miscibility in polymer solvent systems is described. The techniques employed included phase equilibrium measurements and dynamic light scattering and small angle neutron scattering.

  19. Small angle neutron scattering experiments in smectic A and smectic B phases of diluted liquid crystal copolysiloxanes

    NASA Astrophysics Data System (ADS)

    Lecommandoux, S.; Noirez, L.; Mauzac, M.; Hardouin, F.

    1994-12-01

    Small Angle Neutron Scattering experiments were carried out on liquid crystal “side-end fixed” polysiloxanes : we observe that the polymer backbone keeps an oblate shape in the smectic A phase when the proportion of mesogens is reduced. This behavior is different from “side-on fixed” polymers since their anisotropic conformation vanishes at low mesogenic rate. Finally, we show for the first time an oblate anisotropic conformation in the smectic B phase. Par diffusion des neutrons aux petits angles, nous observons que la chaîne de polysiloxanes “en peigne” conserve une conformation de type oblate en phase smectique A lorsqu'on diminue le nombre de mésogènes par unité répétée. Ce comportement est différent de celui des polymères “en haltère” puisqu'à taux de mésogènes équivalent, ces derniers perdent toute anisotropie. Enfin, nous montrons pour la première fois l'existence d'une anisotropie de type oblate en phase smectique B.

  20. Membrane fusogenic activity of the Alzheimer's peptide A beta(1-42) demonstrated by small-angle neutron scattering.

    PubMed

    Dante, Silvia; Hauss, Thomas; Brandt, Astrid; Dencher, Norbert A

    2008-02-15

    Amyloid-beta peptide (A beta) is considered a triggering agent of Alzheimer's disease. In relation to a therapeutic treatment of the disease, the interaction of A beta with the cell membrane has to be elucidated at the molecular level to understand its mechanism of action. In previous works, we had ascertained by neutron diffraction on stacked lipid multilayers that a toxic fragment of A beta is able to penetrate and perturb the lipid bilayer. Here, the influence of A beta(1-42), the most abundant A beta form in senile plaques, on unilamellar lipid vesicles of phospholipids is investigated by small-angle neutron scattering. We have used the recently proposed separated form factor method to fit the data and to obtain information about the vesicle diameter and structure of the lipid bilayer and its change upon peptide administration. The lipid membrane parameters were obtained with different models of the bilayer profile. As a result, we obtained an increase in the vesicle radii, indicating vesicle fusion. This effect was particularly enhanced at pH 7.0 and at a high peptide/lipid ratio. At the same time, a thinning of the lipid bilayer occurred. A fusogenic activity of the peptide may have very important consequences and may contribute to cytotoxicity by destabilizing the cell membrane. The perturbation of the bilayer structure suggests a strong interaction and/or insertion of the peptide into the membrane, although its localization remains beyond the limit of the experimental resolution.

  1. Analysis and simulation of a small-angle neutron scattering instrument on a 1 MW long pulse spallation source

    SciTech Connect

    Olah, G.A.; Hjelm, R.P.; Lujan, M. Jr.

    1996-12-31

    We studied the design and performance of a small-angle neutron scattering (SANS) instrument for a proposed 1 MW, 60 Hz long pulsed spallation source at the Los Alamos Neutron Science Center (LANSCE). An analysis of the effects of source characteristics and chopper performance combined with instrument simulations using the LANSCE Monte Carlo instrument simulations package shows that the T{sub 0} chopper should be no more than 5 m from the source with the frame overlap and frame definition choppers at 5.6 and greater than 7 m, respectively. The study showed that an optimal pulse structure has an exponential decaying tail with {tau} {approx} 750 {mu}s. The Monte Carlo simulations were used to optimize the LPSS SANS, showing that an optimal length is 18 m. The simulations show that an instrument with variable length is best to match the needs of a given measurement. The performance of the optimized LPSS instrument was found to be comparable with present world standard instruments.

  2. Interaction between surfactants and colloidal latexes in nonpolar solvents studied using contrast-variation small-angle neutron scattering.

    PubMed

    Smith, Gregory N; Alexander, Shirin; Brown, Paul; Gillespie, David A J; Grillo, Isabelle; Heenan, Richard K; James, Craig; Kemp, Roger; Rogers, Sarah E; Eastoe, Julian

    2014-04-01

    The interaction between deuterium-labeled Aerosol OT surfactant (AOT-d34) and sterically stabilized poly(methyl methacrylate) (PMMA) latex particles dispersed in nonpolar solvents has been studied using contrast-variation small-angle neutron scattering (CV-SANS). The electrophoretic mobilities (μ) of the latexes have been measured by phase-analysis light scattering, indicating that μ is negative. Two analogues of the stabilizers for the particles have been studied as free polymers in the absence of PMMA latexes: poly(12-hydroxystearic acid) (PHSA) polyester and poly(methyl methacrylate)-graft-poly(12-hydroxystearic acid) (PMMA-graft-PHSA) stabilizer copolymer. The scattering from both PHSA in dodecane and PMMA-graft-PHSA in toluene is consistent with extended polymer chains in good solvents. In dodecane, PMMA-graft-PHSA forms polymer micelles, and SANS is consistent with ellipsoidal aggregates formed of around 50 polymer chains. CV-SANS measurements were performed by measuring SANS from systems of PHSA, PMMA-graft-PHSA, and PMMA latexes with 10 and 100 mM surfactant solutions of AOT-d34 in both polymer/particle and AOT contrast-matched solvent. No excess scattering above the polymer or surfactant was found for PHSA in dodecane or PMMA-graft-PHSA in dodecane and toluene. This indicates that AOT does not significantly interact with the free polymers. Excess scattering was observed for systems with AOT-d34 and PMMA latexes dispersed in particle contrast-matched dodecane, consistent with the penetration of AOT into the PMMA latexes. This indicates that AOT does not interact preferentially with the stabilizing layers but, rather, is present throughout the colloids. Previous research ( Langmuir 2010, 26, 6967-6976 ) suggests that AOT surfactant is located in the latex PHSA-stabilizer layer, but all the results in this study are consistent with AOT poorly interacting with alkyl-stabilizer polymers.

  3. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique.

    PubMed

    Sakuma, Y; Urakami, N; Taniguchi, T; Imai, M

    2011-07-20

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  4. The spatial diamond-graphite transition in detonation nanodiamond as revealed by small-angle neutron scattering.

    PubMed

    Avdeev, Mikhail V; Aksenov, Victor L; Tomchuk, Oleksandr V; Bulavin, Leonid A; Garamus, Vasil M; Osawa, Eiji

    2013-11-06

    A spatial transition of the carbon state in detonation nanodiamond (DND) from crystalline diamond inside the particle to a graphite-like state at the DND surface is proposed on the basis of small-angle neutron scattering (SANS) analysis. The SANS contrast variation from concentrated (5 wt%) dispersions of DND in liquids (water, dimethylsulfoxide) reveals a shift in the mean scattering length density of DND as compared to pure diamond, which is related to the presence of a non-diamond component in the DND structure. At the same time, the diffusive character of the particle surface is deduced based on the deviation from the Porod law. The two observations are combined to conclude that the continuous radial density profile over the whole particle volume conforms to a simple power law. The profile naturally suggests that non-diamond states are concentrated mainly close to the particle surface; still there is no sharp boundary between the radial distributions of the two states of carbon in DND.

  5. The structure of Sindbis virus produced from vertebrate and invertabrate hosts determined by small angle neutron scattering

    SciTech Connect

    He, Lilin; Piper, Amanda; Meilleur, Flora; Myles, Dean A A; Hernandez, Raquel; Brown, Dennis; Heller, William T

    2010-01-01

    The complex natural cycle of vectored viruses that transition between host species, such as between insects and mammals, makes understanding the full life cycle of the virus an incredibly complex problem. Sindbis virus, an arbovirus and prototypic alphavirus having an inner protein shell and an outer glycoprotein coat separated by a lipid membrane, is one example of a vectored virus that transitions between vertebrate and insect hosts. While evidence of host-specific differences in Sindbis virus has been observed, no work has been performed to characterize the impact of the host species on the structure of the virus. Here, we report the first study of the structural differences between Sindbis viruses grown in mammalian and insect cells, which were determined by small-angle neutron scattering (SANS), a nondestructive technique that did not decrease the infectivity of the Sindbis virus particles studied. The scattering data and modeling showed that, while the radial position of the lipid bilayer did not change significantly, it was possible to conclude that it did have significantly more cholesterol when the virus was grown in mammalian cells. Additionally, the outer protein coat was found to be more extended in the mammalian Sindbis virus. The SANS data also demonstrated that the RNA and nucleocapsid protein share a closer interaction in the mammalian-cell-grown virus than in the virus from insect cells.

  6. Conformational effect on small angle neutron scattering behavior of interacting polyelectrolyte solutions: a perspective of integral equation theory

    SciTech Connect

    Chen, Wei-Ren; Do, Changwoo; Hong, Kunlun; Liu, Yun; Porcar, L.; Shew, Chwen-Yang; Smith, Greg

    2012-01-01

    We present small angle neutron scattering (SANS) measurements of deuterium oxide (D2O) solutions of linear and star sodium poly(styrene sulfonate) (NaPSS) as a function of polyelectrolyte concentration. Emphasis is on understanding the dependence of their SANS coherent scattering cross section I(Q) on the molecular architecture of single polyelectrolyte. The key finding is that for a given concentration, star polyelectrolytes exhibit more pronounced characteristic peaks in I(Q), and the position of the first peak occurs at a smaller Q compared to their linear counterparts. Based on a model of integral equation theory, we first compare the SANS experimental I(Q) of salt free polyelectrolyte solutions with that predicted theoretically. Having seen their satisfactory qualitative agreement, the dependence of counterion association behavior on polyelectrolyte geometry and concentration is further explored. Our predictions reveal that the ionic environment of polyelectrolyte exhibits a strong dependence on polyelectrolyte geometry at lower polyelectrolyte concentration. However, when both linear and star polyelectrolytes exceed their overlap concentrations, the spatial distribution of counterion is found to be essentially insensitive to polyelectrolyte geometry due to the steric effect.

  7. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique

    NASA Astrophysics Data System (ADS)

    Sakuma, Y.; Urakami, N.; Taniguchi, T.; Imai, M.

    2011-07-01

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  8. Comparative analysis of the structure of sterically stabilized ferrofluids on polar carriers by small-angle neutron scattering.

    PubMed

    Avdeev, M V; Aksenov, V L; Balasoiu, M; Garamus, V M; Schreyer, A; Török, Gy; Rosta, L; Bica, D; Vékás, L

    2006-03-01

    Results of experiments on small-angle neutron scattering from ferrofluids on polar carriers (pentanol, water, methyl-ethyl-ketone), with double-layer sterical stabilization of magnetic nanoparticles, are reported. Several types of spatial structural organization are observed. The structure of highly stable pentanol-based samples is similar to that of stable ferrofluids based on organic non-polar carriers (e.g., benzene) with mono-layer covered magnetic nanoparticles. At the same time, the effect of the interparticle interaction on the scattering is stronger in polar ferrofluids because of the structural difference in the surfactant shell. The structure of the studied methyl-ethyl-ketone- and water-based ferrofluids essentially different from the previous case. The formation of large (>100 nm in size) elongated or fractal aggregates, respectively, is detected even in the absence of external magnetic field, which corresponds to weaker stability of these types of ferrofluids. The structure of the fractal aggregates in water-based ferrofluids does not depend on the particle concentration, but it is sensitive to temperature. A temperature increase results in a decrease in their fractal dimension reflecting destruction of the aggregates. In addition, in water-based ferrofluids these aggregates consist of small (radius approximately 10 nm) and temperature-stable primary aggregates.

  9. Hidden quantum phase transition in Mn1 -xFexGe evidenced by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Altynbaev, E.; Siegfried, S.-A.; Moskvin, E.; Menzel, D.; Dewhurst, C.; Heinemann, A.; Feoktystov, A.; Fomicheva, L.; Tsvyashchenko, A.; Grigoriev, S.

    2016-11-01

    The magnetic system of the Mn1 -xFexGe solid solution is ordered in a spiral spin structure in the whole concentration range of x ∈[0 ÷1 ] . The close inspection of the small-angle neutron-scattering data reveals the quantum phase transition from the long-range ordered to short-range ordered helical structure upon increase of Fe concentration at x ∈[0.25 ÷0.4 ] . The short-range order (SRO) of the helical structure is identified as a Lorentzian contribution, while long-range order is associated with the Gaussian contribution into the scattering profile function. The scenario of the quantum phase transition with x as a driving parameter is similar to the thermal phase transition in pure MnGe. The quantum nature of the SRO is proved by the temperature-independent correlation length of the helical structure at low- and intermediate-temperature ranges with remarkable decrease above certain temperature TQ. We suggest the x -dependent modification of the effective Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model of magnetism to explain the quantum critical regime in Mn1 -xFexGe .

  10. Small-Angle Neutron Scattering Investigation of Growth Modifiers on Hydrate Crystal Surfaces

    NASA Astrophysics Data System (ADS)

    Sun, Thomas; Hutter, Jeffrey L.; Lin, M.; King, H. E., Jr.

    1998-03-01

    Hydrates are crystals consisting of small molecules enclathrated within an ice-like water cage. Suppression of their growth is important in the oil industry. The presence of small quantities of specific polymers during hydrate crystallization can induce a transition from an octahedral to planar growth habit. This symmetry breaking is surprising because of the suppression of two 111 planes relative to the other six crystallographically equivalent faces. To better understand the surface effects leading to this behavior, we have studied the surface adsorption of these growth-modifing polymers onto the hydrate crytals using SANS. The total hydrate surface area, as measured by Porod scattering, increases in the presence of the growth modifier, but, no significant increase in polymer concentration on the crystal surfaces is found. Implications for possible growth mechanisms will be discussed.

  11. Membrane Structure Studies by Means of Small-Angle Neutron Scattering (SANS)

    NASA Astrophysics Data System (ADS)

    Knott, R. B.

    2008-03-01

    The basic model for membrane structure—a lipid bilayer with imbedded proteins—was formulated 35 years ago, however the detailed structure is still under active investigation using a variety of physical, chemical and computational techniques. Every biologically active cell is encapsulated by a plasma membrane with most cells also equipped with an extensive intracellular membrane system. The plasma membrane is an important boundary between the cytoplasm of the cell and the external environment, and selectively isolates the cell from that environment. Passive diffusion and/or active transport mechanisms are provided for water, ions, substrates etc. which are vital for cell metabolism and viability. Membranes also facilitate excretion of substances either as useful cellular products or as waste. Despite their complexity and diverse function, plasma membranes from quite different cells have surprisingly similar compositions. A typical membrane structure consists of a phospholipid bilayer with a number of proteins scattered throughout, along with carbohydrates (glycoproteins), glycolipids and sterols. The plasma membranes of most eukaryotic cells contain approximately equal weights of lipid and protein, which corresponds to about 100 lipid molecules per protein molecule. Clearly, lipids are a major constituent and the study of their structure and function in isolation provides valuable insight into the more complex intact multic

  12. Salt-dependent DNA superhelix diameter studied by small angle neutron scattering measurements and Monte Carlo simulations.

    PubMed Central

    Hammermann, M; Brun, N; Klenin, K V; May, R; Tóth, K; Langowski, J

    1998-01-01

    Using small angle neutron scattering we have measured the static form factor of two different superhelical DNAs, p1868 (1868 bp) and pUC18 (2686 bp), in dilute aqueous solution at salt concentrations between 0 and 1.5 M Na+ in 10 mM Tris at 0% and 100% D2O. For both DNA molecules, the theoretical static form factor was also calculated from an ensemble of Monte Carlo configurations generated by a previously described model. Simulated and measured form factors of both DNAs showed the same behavior between 10 and 100 mM salt concentration: An undulation in the scattering curve at a momentum transfer q = 0.5 nm-1 present at lower concentration disappears above 100 mM. The position of the undulation corresponds to a distance of approximately 10-20 nm. This indicated a change in the DNA superhelix diameter, as the undulation is not present in the scattering curve of the relaxed DNA. From the measured scattering curves of superhelical DNA we estimated the superhelix diameter as a function of Na+ concentration by a quantitative comparison with the scattering curve of relaxed DNA. The ratio of the scattering curves of superhelical and relaxed DNA is very similar to the form factor of a pair of point scatterers. We concluded that the distance of this pair corresponds to the interstrand separation in the superhelix. The computed superhelix diameter of 16.0 +/- 0.9 nm at 10 mM decreased to 9.0 +/- 0.7 nm at 100 mM salt concentration. Measured and simulated scattering curves agreed almost quantitatively, therefore we also calculated the superhelix diameter from the simulated conformations. It decreased from 18.0 +/- 1.5 nm at 10 mM to 9.4 +/- 1.5 nm at 100 mM salt concentration. This value did not significantly change to lower values at higher Na+ concentration, in agreement with results obtained by electron microscopy, scanning force microscopy imaging in aqueous solution, and recent MC simulations, but in contrast to the observation of a lateral collapse of the DNA superhelix

  13. Small-Angle Neutron Scattering (SANS) Facility at BATAN for Nanostructure Studies in Materials Science and Biology

    NASA Astrophysics Data System (ADS)

    Putra, E. Giri Rachman

    2010-01-01

    A 36 meter small-angle neutron scattering (SANS) BATAN spectrometer (SMARTer) which is the second largest SANS spectrometer nowadays in the Asia-Oceania region was constructed at the neutron scattering laboratory (NSL) in Serpong, Indonesia. Lots of works on replacing, upgrading and improving the control system, experimental methods, data collection and reduction in the last three years have been carried out to revitalize and then optimize the performance of SMARTer. At first, some standard samples were measured for the inter-laboratory comparison and several kinds of substances such as liquid, gel, powder, and solid-state thin film have been investigated recently of proposed research interest. The morphological changes from ellipsoidal into cylindrical (worm-like) micelles of self-assembly amphiphilic molecules, sodium dodecyl sulfate (SDS) and transformation of disordered into ordered spherical micelle system from unimer Gaussian coils of PEO-PPO-PEO triblock copolymers (Pluronics) in solution by salt addition were also observed. Particle size and its distribution of spherical polystyrene latex and silica nanoparticles in dilute solution have been simply distinguished by applying a spherical calculation model. Bragg peaks which correspond to a lamellar structure was revealed from a powder sample of silver behenate [CH3(CH2)20COOAg] nanoparticle and a solid-state PS-PEP, polystyrene-b-poly(ethylene-alt-propylene), diblock copolymer film. The growth mechanism and fractal structures from aggregation of nanoparticles such as Fe3O4 ferrofluids or titanium-silica aerogels were investigated directly using a SANS technique through a power-law scattering of fractal structures approximation fitted at their scattering profiles. Meanwhile, magnetic structure from metal-alloys, CuNiFe showing anisotropic magnetic scattering structure properties up to 1 Tesla of external magnetic field was also accomplished confirming the nanocrystalline and magnetic domain sizes. The detail

  14. Small angle neutron scattering reveals pH-dependent conformational changes in Trichoderma reesei cellobiohydrolase I: implications for enzymatic activity.

    PubMed

    Pingali, Sai Venkatesh; O'Neill, Hugh M; McGaughey, Joseph; Urban, Volker S; Rempe, Caroline S; Petridis, Loukas; Smith, Jeremy C; Evans, Barbara R; Heller, William T

    2011-09-16

    Cellobiohydrolase I (Cel7A) of the fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) hydrolyzes crystalline cellulose to soluble sugars, making it of key interest for producing fermentable sugars from biomass for biofuel production. The activity of the enzyme is pH-dependent, with its highest activity occurring at pH 4-5. To probe the response of the solution structure of Cel7A to changes in pH, we measured small angle neutron scattering of it in a series of solutions having pH values of 7.0, 6.0, 5.3, and 4.2. As the pH decreases from 7.0 to 5.3, the enzyme structure remains well defined, possessing a spatial differentiation between the cellulose binding domain and the catalytic core that only changes subtly. At pH 4.2, the solution conformation of the enzyme changes to a structure that is intermediate between a properly folded enzyme and a denatured, unfolded state, yet the secondary structure of the enzyme is essentially unaltered. The results indicate that at the pH of optimal activity, the catalytic core of the enzyme adopts a structure in which the compact packing typical of a fully folded polypeptide chain is disrupted and suggest that the increased range of structures afforded by this disordered state plays an important role in the increased activity of Cel7A through conformational selection.

  15. Molecular conformation of the full-length tumor suppressor NF2/Merlin—a small angle neutron scattering study

    PubMed Central

    Khajeh, Jahan Ali; Ju, Jeong Ho; Atchiba, Moussoubaou; Allaire, Marc; Stanley, Christopher; Heller, William T.; Callaway, David J.E.; Bu, Zimei

    2014-01-01

    Summary The tumor suppressor protein Merlin inhibits cell proliferation upon establishing cell-cell contacts. Because Merlin has high sequence similarity to the Ezrin-Radixin-Moesin (ERM) family of proteins, the structural model of ERM protein autoinhibition and cycling between closed/resting and open/active conformational states is often employed to explain Merlin function. However, recent biochemical studies suggest alternative molecular models of Merlin function. Here, we have determined the low resolution molecular structure and binding activity of Merlin and a Merlin(S518D) mutant that mimics the inactivating phosphorylation at S518 using small angle neutron scattering (SANS) and binding experiments. SANS shows that in solution both Merlin and Merlin(S518D) adopt a closed conformation, but binding experiments indicate that a significant fraction of either Merlin or Merlin(S518D) is capable of binding to the target protein NHERF1. Upon binding to the phosphatidylinositol 4,5-bisphosphate lipid, the wild-type Merlin adopts a more open conformation than in solution, but Merlin(S518D) remains in a closed conformation. This study supports a rheostat model of Merlin in NHERF1 binding, and contributes to resolve a controversy about the molecular conformation and binding activity of Merlin. PMID:24882693

  16. Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment

    NASA Astrophysics Data System (ADS)

    Palit, Swomitra; He, Lilin; Hamilton, William A.; Yethiraj, Arun; Yethiraj, Anand

    2017-03-01

    The effect of particles on the behavior of polymers in solution is important in a number of important phenomena such as the effect of "crowding" proteins in cells, colloid-polymer mixtures, and nanoparticle "fillers" in polymer solutions and melts. In this Letter, we study the effect of spherical inert nanoparticles (which we refer to as "crowders") on the diffusion coefficient and radius of gyration of polymers in solution using pulsed-field-gradient NMR and small-angle neutron scattering (SANS), respectively. The diffusion coefficients exhibit a plateau below a characteristic polymer concentration, which we identify as the overlap threshold concentration c⋆. Above c⋆, in a crossover region between the dilute and semidilute regimes, the (long-time) self-diffusion coefficients are found, universally, to decrease exponentially with polymer concentration at all crowder packing fractions, consistent with a structural basis for the long-time dynamics. The radius of gyration obtained from SANS in the crossover regime changes linearly with an increase in polymer concentration, and must be extrapolated to c⋆ in order to obtain the radius of gyration of an individual polymer chain. When the polymer radius of gyration and crowder size are comparable, the polymer size is very weakly affected by the presence of crowders, consistent with recent computer simulations. There is significant chain compression, however, when the crowder size is much smaller than the polymer radius gyration.

  17. Conformational changes in Sindbis virus induced by decreased pH revealed by small-angle neutron scattering

    SciTech Connect

    Hernandez, Raquel; He, Lilin; Piper, Amanda; Meilleur, Flora; Brown, Dennis; Heller, William T

    2012-01-01

    Alphaviruses, such as Sindbis virus, undergo dramatic changes in three-dimensional structure upon exposure to low pH, and such exposure can establish conditions allowing fusion of the virus membrane with a cell plasma membrane upon return to neutral pH. While exposure to low pH is not required for entry of Sindbis virus into vertebrate or invertebrate cells, the conformational changes occurring at low pH may mimic those occurring upon virus-receptor interaction. Here, we employed small-angle neutron scattering with contrast variation to probe how the structure of a mammalian-grown Sindbis virus responds to moderately acidic pH. Several changes took place throughout the virion structure when the pH decreased from 7.2 to 6.4. Specifically, the RNA in the virion core underwent a conformational change. Additionally, the protein was redistributed. A significant amount of protein moved from the layer containing the lipid bilayer to the exterior of the virion. The results improve our understanding of the pH-driven alteration of Sindbis virus structure.

  18. Ultra-small-angle neutron scattering: a tool to study packing of relatively monodisperse polymer spheres and their binary mixtures.

    PubMed

    Reynolds, Philip A; McGillivray, Duncan J; Jackson, Andrew J; White, John W

    2009-07-01

    We measured ultra-small-angle neutron scattering (USANS) from polymethylmethacrylate spheres tamped down in air. Two slightly polydisperse pure sphere sizes (1.5 and 7.5 microm diameters) and five mixtures of these were used. All were loose packed (packing fractions of 0.3-0.6) with nongravitational forces (e.g., friction) important, preventing close packing. The USANS data are rich in information on powder packing. A modified Percus-Yevick fluid model was used to parametrize the data-adequately but not well. The modifications required the introduction of small voids, less than the sphere size, and a parameter reflecting substantial deviation from the Percus-Yevick prediction of the sphere-sphere correlation function. The mixed samples fitted less well, and two further modifying factors were necessary. These were local inhomogeneities, where the concentration of same-size spheres, both large and small, deviated from the mean packing, and a factor accounting for the presence within these "clusters" of self-avoidance of the large spheres (that is, large spheres coated with more small spheres than Percus-Yevick would predict). The overall deviations from the hard-sphere Percus-Yevick model that we find here suggest that fluid models of loose packed powders are unlikely to be successful but lay the ground work for future theoretical and computational works.

  19. Small angle neutron scattering study of the conformation of poly(ethylene oxide) dissolved in deep eutectic solvents.

    PubMed

    Chen, Zhengfei; McDonald, Samila; FitzGerald, Paul; Warr, Gregory G; Atkin, Rob

    2017-11-15

    The conformation of poly(ethylene oxide) (PEO) in deep eutectic solvents (DESs) is determined by the polymer-solvent interactions, especially hydrogen bonding interactions. The hypothesis for this work is that the hydrogen bonding environment of a DES can be varied via changing the cation or hydrogen bond donor (HBD), and therefore the solvent quality for PEO; the anion species will also effect hydrogen bonding, but this is not examined here. Small angle neutron scattering (SANS) is used to probe the concentration dependent conformation of 36kDa PEO dissolved in DESs formed by mixing ethyl or butyl ammonium bromide with a molecular HBD (glycerol or ethylene glycol) in a 1:2 molar ratio. The radius of gyration (Rg), Flory exponent and crossover concentration (c(*)) from the dilute to the semi-dilute regime of PEO in the DESs revealed by SANS and Zimm plot analysis show that these DESs are moderately good solvents for PEO. When the ammonium alkyl chain length is increased, the hydrogen bond density per unit volume decreases, and with it the solvent quality for PEO. The solvent quality is improved when the HBD is changed from glycerol to ethylene glycol due to differences in the hydrogen bonding environment for PEO. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment.

    PubMed

    Palit, Swomitra; He, Lilin; Hamilton, William A; Yethiraj, Arun; Yethiraj, Anand

    2017-03-03

    The effect of particles on the behavior of polymers in solution is important in a number of important phenomena such as the effect of "crowding" proteins in cells, colloid-polymer mixtures, and nanoparticle "fillers" in polymer solutions and melts. In this Letter, we study the effect of spherical inert nanoparticles (which we refer to as "crowders") on the diffusion coefficient and radius of gyration of polymers in solution using pulsed-field-gradient NMR and small-angle neutron scattering (SANS), respectively. The diffusion coefficients exhibit a plateau below a characteristic polymer concentration, which we identify as the overlap threshold concentration c^{⋆}. Above c^{⋆}, in a crossover region between the dilute and semidilute regimes, the (long-time) self-diffusion coefficients are found, universally, to decrease exponentially with polymer concentration at all crowder packing fractions, consistent with a structural basis for the long-time dynamics. The radius of gyration obtained from SANS in the crossover regime changes linearly with an increase in polymer concentration, and must be extrapolated to c^{⋆} in order to obtain the radius of gyration of an individual polymer chain. When the polymer radius of gyration and crowder size are comparable, the polymer size is very weakly affected by the presence of crowders, consistent with recent computer simulations. There is significant chain compression, however, when the crowder size is much smaller than the polymer radius gyration.

  1. Peptide-induced Asymmetric Distribution of Charged Lipids in a Vesicle Bilayer Revealed by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Heller, William; Qian, Shuo

    2012-02-01

    Cellular membranes are complex mixtures of lipids, proteins and other small molecules that provide functional, dynamic barriers between the cell and its environment, as well as between environments within the cell. The lipid composition of the membrane is highly specific and controlled in terms of both content and lipid localization. Here, small-angle neutron scattering and selective deuterium labeling were used to probe the impact of the membrane-active peptides melittin and alamethicin on the structure of lipid bilayers composed of a mixture of the lipids dimyristoyl phosphatidylglycerol (DMPG) and chain-perdeuterated dimyristoyl phosphatidylcholine (DMPC). We found that both peptides enriched the outer leaflet of the bilayer with the negatively charged DMPG, creating an asymmetric distribution of lipids. The level of enrichment is peptide concentration-dependent and is stronger for melittin than alamethicin. The enrichment between the inner and outer bilayer leaflets occurs at very low peptide concentrations, and increases with peptide concentration, including when the peptide adopts a membrane-spanning, pore-forming state.

  2. Small angle neutron scattering study of sodium dodecyl sulfate micellar growth driven by addition of a hydrotropic salt.

    PubMed

    Hassan, P A; Fritz, Gerhard; Kaler, Eric W

    2003-01-01

    The structures of aggregates formed in aqueous solutions of an anionic surfactant, sodium dodecyl sulfate (SDS), with the addition of a cationic hydrotropic salt, p-toluidine hydrochloride (PTHC), have been investigated by small angle neutron scattering (SANS). The SANS spectra exhibit a pronounced peak at low salt concentration, indicating the presence of repulsive intermicellar interactions. Model-independent real space information about the structure is obtained from a generalized indirect Fourier transformation (GIFT) technique in combination with a suitable model for the interparticle structure factor. The interparticle interaction is captured using the rescaled mean spherical approximation (RMSA) closure relation and a Yukawa form of the interaction potential. Further quantification of the geometrical parameters of the micelles was achieved by a complete fit of the SANS data using a prolate ellipsoidal form factor and the RMSA structure factor. The present study shows that PTHC induces a decrease in the fractional charge of the micelles due to adsorption at the micellar surface and consequent growth of the SDS micelles from nearly globular to rodlike as the concentration of PTHC increases.

  3. Structural changes in C–S–H gel during dissolution: Small-angle neutron scattering and Si-NMR characterization

    SciTech Connect

    Trapote-Barreira, Ana; Porcar, Lionel; Cama, Jordi; Soler, Josep M.; Allen, Andrew J.

    2015-06-15

    Flow-through experiments were conducted to study the calcium–silicate–hydrate (C–S–H) gel dissolution kinetics. During C–S–H gel dissolution the initial aqueous Ca/Si ratio decreases to reach the stoichiometric value of the Ca/Si ratio of a tobermorite-like phase (Ca/Si = 0.83). As the Ca/Si ratio decreases, the solid C–S–H dissolution rate increases from (4.5 × 10{sup −} {sup 14} to 6.7 × 10{sup −} {sup 12}) mol m{sup −} {sup 2} s{sup −} {sup 1}. The changes in the microstructure of the dissolving C–S–H gel were characterized by small-angle neutron scattering (SANS) and {sup 29}Si magic-angle-spinning nuclear magnetic resonance ({sup 29}Si-MAS NMR). The SANS data were fitted using a fractal model. The SANS specific surface area tends to increase with time and the obtained fit parameters reflect the changes in the nanostructure of the dissolving solid C–S–H within the gel. The {sup 29}Si MAS NMR analyses show that with dissolution the solid C–S–H structure tends to a more ordered tobermorite structure, in agreement with the Ca/Si ratio evolution.

  4. Structural Evolution of Polylactide Molecular Bottlebrushes: Kinetics Study by Size Exclusion Chromatography, Small Angle Neutron Scattering and Simulations

    SciTech Connect

    Pickel, Deanna L; Kilbey, II, S Michael; Uhrig, David; Hong, Kunlun; Carrillo, Jan-Michael Y; Sumpter, Bobby G; Ahn, Suk-Kyun; Han, Youngkyu; Kim, Dr. Tae-Hwan; Smith, Gregory Scott; Do, Changwoo

    2014-01-01

    Structural evolution from poly(lactide) (PLA) macromonomer to resultant PLA molecular bottlebrush during ring opening metathesis polymerization (ROMP) was investigated for the first time by combining size exclusion chromatography (SEC), small-angle neutron scattering (SANS) and coarse-grained molecular dynamics (CG-MD) simulations. Multiple aliquots were collected at various reaction times during ROMP, and subsequently analyzed by SEC and SANS. The two complementary techniques enable the understanding of systematic changes in conversion, molecular weight and dispersity as well as structural details of PLA molecular bottlebrushes. CG-MD simulation not only predicts the experimental observations, but it also provides further insight into the analysis and interpretation of data obtained in SEC and SANS experiments. We find that PLA molecular bottlebrushes undergo three conformational transitions with increasing conversion (i.e., increasing the backbone length): (1) from an elongated to a globular shape due to longer side chain at lower conversion, (2) from a globular to an elongated shape at intermediate conversion caused by excluded volume of PLA side chain, and (3) the saturation of contour length at higher conversion due to chain transfer reactions.

  5. Monitoring phase behavior of hydrogen confined in carbon nanopores by in-situ small angle neutron scattering technique

    SciTech Connect

    Zhang, Hongxin; He, Lilin; Melnichenko, Yuri B; Contescu, Cristian I; Gallego, Nidia C

    2012-01-01

    We report on the use of in-situ small angle neutron scattering (SANS) technique to study the phase behavior of hydrogen confined in narrow pores of ultramicroporous carbon (UMC) with a very large surface area (2630 m2/g) and pore volume (1.3 cm3/g). The effect of pore size and pressure on hydrogen adsorbed on UMC at room temperature and pressures up to ~200 bar were investigated. In a previous experiment, we have measured the density of adsorbed H2 gas in the nanopores and mesopores of polyfurfuryl alcohol-derived activated carbon (PFAC) by SANS techniques. Here, a comparative SANS study between the UMC and PFAC was conducted in order to further investigate the densification of H2 as a function of pore size and pressure. Initial results suggest that the density of confined H2 in both UMC and PFAC is considerably higher than that of the bulk hydrogen gas. The density is systematically higher in the narrow pores and decreases with increasing pore size. These results clearly demonstrate the advantage of adsorptive storage over compressed gas storage and emphasize the greater efficiency of micropores over mesopores in the adsorption process, which can be used to guide the development of new carbon adsorbents tailored for maximum H2 storage capacities at near-ambient temperatures.

  6. Growth Kinetics of Lipid-Based Nanodiscs to Unilamellar Vesicles: A Time-Resolved Small Angle Neutron Scattering (SANS) Study

    SciTech Connect

    Mahabir, Suanne; Small, Darcy; Li, Ming; Wan, Wankei; Kucerka, Norbert; Littrell, Ken; Katsaras, John; Nieh, Mu-Ping

    2013-01-01

    Mixtures of dimyristoyl-phosphatidylcholine (DMPC), dimyristoyl-phosphatidylglycerol (DMPG) and dihexanoylphosphatidylcholine (DHPC) in aqueous solutions spontaneously form monodisperse, bilayered nanodiscs (also known as bicelles ) at or below the melting transition temperature of DMPC (TM ~23 C). In dilute systems above the main transition temperature TM of DMPC, bicelles coalesce (increasing their diameter) and eventually self-fold into unilamellar vesicles (ULVs). Time resolved small angle neutron scattering was used to study the growth kinetics of nanodiscs below and equal to TM over a period of hours as a function of temperature at two lipid concentrations in presence or absence of NaCl salt. Bicelles seem to undergo a sudden initial growth phase with increased temperature, which is then followed by a slower reaction-limited growth phase that depends on ionic strength, lipid concentration and temperature. The bicelle interaction energy was derived from the colloidal theory of Derjaguin and Landau, and Verwey and Overbeek (DLVO). While the calculated total energy between discs is attractive and proportional to their growth rate, a more detailed mechanism is proposed to describe the mechanism of disc coalescence. After annealing at low temperature (low-T), samples were heated to 50 C in order to promote the formation of ULVs. Although the low-T annealing of samples has only a marginal effect on the mean size of end-state ULVs, it does affect their polydispersity, which increases with increased T, presumably driven by the entropy of the system.

  7. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

    SciTech Connect

    Wirth, B D; Asoka-Kumar, P; Howell, R H; Odette, G R; Sterne, P A

    2001-01-01

    Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime ({approx}500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.

  8. Structure and interparticle interactions of bovine serum albumin in solution studied by small-angle neutron scattering

    SciTech Connect

    Bendedouch, D.; Chen, S.H.

    1983-04-28

    A series of small-angle neutron scattering (SANS) measurements were carried out on dilute and moderately concentrated bovine serum albumin (BSA) solutions at two different pH values and at t = 35/sup 0/C. The amount of bound water to the protein was deduced from the zero-contrast point of dilute BSA solutions, in D/sub 2/O and H/sub 2/O solvent mixtures. Detailed analysis of the intensity spectrum from the most dilute BSA solution in D/sub 2/O yields a prolate ellipsoidal shape (a,b,b) of the protein molecule with a = 70 angstrom and b = 20 angstrom. At moderate concentrations, pH 7, with or without salt (LiCl) added, the intensity spectra can be fitted satisfactorily by taking into account both the ellipsoidal shape of the particle and an interparticle interference factor (S(Q)). Calculation of S(Q) assumes a model of equivalent charged hard spheres interacting through a repulsive potential. For moderately concentrated solutions at pH 5.1, S(Q) can be accounted for by introducing an attractive potential between the particles.

  9. Structural Evolution of Polylactide Molecular Bottlebrushes: Kinetics Study by Size Exclusion Chromatography, Small Angle Neutron Scattering, and Simulations

    SciTech Connect

    Ahn, Suk-kyun; Carrillo, Jan-Michael Y.; Han, Youngkyu; Kim, Tae-Hwan; Uhrig, David; Pickel, Deanna L.; Hong, Kunlun; S. Michael Kilbey; Sumpter, Bobby G.; Smith, Gregory Scott; Do, Changwoo

    2014-08-18

    In this paper, structural evolution from poly(lactide) (PLA) macromonomer to resultant PLA molecular bottlebrush during ring opening metathesis polymerization (ROMP) was investigated for the first time by combining size exclusion chromatography (SEC), small-angle neutron scattering (SANS), and coarse-grained molecular dynamics (CG-MD) simulations. Multiple aliquots were collected at various reaction times during ROMP and subsequently analyzed by SEC and SANS. These complementary techniques enable the understanding of systematic changes in conversion, molecular weight and dispersity as well as structural details of PLA molecular bottlebrushes. CG-MD simulation not only predicts the experimental observations, but it also provides further insight into the analysis and interpretation of data obtained in SEC and SANS experiments. Finally, we find that PLA molecular bottlebrushes undergo three conformational transitions with increasing conversion (i.e., increasing the backbone length): (1) from an elongated to a globular shape due to longer side chain at low conversion, (2) from a globular to an elongated shape at intermediate conversion caused by excluded volume of PLA side chain, and (3) the saturation of contour length at high conversion due to chain transfer reactions.

  10. Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Siegfried, S.-A.; Sukhanov, A. S.; Altynbaev, E. V.; Honecker, D.; Heinemann, A.; Tsvyashchenko, A. V.; Grigoriev, S. V.

    2017-04-01

    We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225 K up to TC≈278.7 K by small-angle neutron scattering. The method we have used is based on [Grigoriev et al., Phys. Rev. B 92, 220415(R) (2015), 10.1103/PhysRevB.92.220415] and was extended here for the application in polycrystalline samples. We confirm the validity of the anisotropic spin-wave dispersion for FeGe caused by the Dzyaloshinskii-Moriya interaction. We have shown that the spin-wave stiffness A for the FeGe helimagnet decreases with a temperature as A (T ) =194 [1 -0.7 (T/TC) 4.2] meVÅ 2 . The finite value of the spin-wave stiffness A =58 meVÅ 2 at TC classifies the order-disorder phase transition in FeGe as being the first-order one.

  11. Effect of Chain Structure on the Miscibility of Cellulose Acetate Blends. A Small-Angle Neutron Scattering Study

    SciTech Connect

    Dyer, Caleb W.; Jiang, Zhe; Bozell, Joseph J.; Rials, Timothy G.; Heller, William T.; Dadmun, Mark D.

    2013-02-12

    The miscibility of cellulose ester blends with varying degree of substitution (DS) of acetates along the chain backbone has been investigated using small-angle neutron scattering. The difference in degree of substitution (ΔDS) between the two components in the blend was systematically varied from 0.06 to 0.63 where each blend was found to be a partially miscible, two-phase system. Miscibility between the two components initially decreases as ΔDS of the blends increases. The Flory interaction parameter, χ, concurrently increases with increasing ΔDS as a result of diminishing van der Waals forces between components. The cellulose acetates with lower degree of substitution, which contain more hydroxyl substituents, however, demonstrate greater miscibility even at higher ΔDS. This is interpreted to be the result of favorable hydrogen bonding between blend components that are possible in the presence of more hydroxyl groups. FT-IR data support this interpretation, indicating an increase in hydrogen bonding in a blend having a lower DS component. These results indicate that while an increase in structural differences between cellulose acetate blend components limits miscibility, the presence of hydroxyl groups on the chain promotes mixing. This competition accentuates the significant impact specific interactions have on blend miscibility for these copolymers.

  12. Characterization of multimetric variants of ubiquitin carboxyl-terminal hydrolase L1 in water by small-angle neutron scattering

    SciTech Connect

    Naito, Sachio . E-mail: sachio@post.kek.jp; Mochizuki, Hideki; Yasuda, Toru; Mizuno, Yoshikuni; Furusaka, Michihiro; Ikeda, Susumu; Adachi, Tomohiro; Shimizu, Hirohiko M.; Suzuki, Junichi; Fujiwara, Satoru; Okada, Tomoko; Nishikawa, Kaori; Aoki, Shunsuke; Wada, Keiji

    2006-01-13

    Here, we illustrated that the morphological structures of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) variants and Parkinson's disease (PD) exhibit good pathological correlation by a small-angle neutron scattering (SANS). UCH-L1 is a neuro-specific multiple functional enzyme, deubiquitinating, ubiquityl ligase, and also involved in stabilization of mono-ubiquitin. To examine the relationship between multiple functions of UCH-L1 and the configuration of its variants [wild-type, I93M (linked to familial Parkinson's disease), and S18Y (linked to reduced risk of Parkinson's disease)], in this report, we proposed that these were all self-assembled dimers by an application of a rotating ellipsoidal model; the configurations of these dimers were quite different. The wild-type was a rotating ellipsoidal. The globular form of the monomeric component deformed by the I93M mutation. Conversely, the S18Y polymorphism promoted the globularity. Thus, the multiple functional balance is closely linked to the intermolecular interactions between the UCH-L1 monomer and the final dimeric configuration.

  13. Assembly State of Proteasome Activator 28 in an Aqueous Solution as Studied by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Sugiyama, Masaaki; Kurimoto, Eiji; Morimoto, Yukio; Sahashi, Hiroki; Sakata, Eri; Hamada, Kei; Itoh, Keiji; Mori, Kazuhiro; Fukunaga, Toshiharu; Minami, Yasufumi; Kato, Koichi

    2009-12-01

    The characterization of quaternary structures of proteins in solution remains challenging, especially for those undergoing dynamic changes. Small-angle neutron scattering (SANS) is a potentially powerful method for addressing this issue with little perturbation resulting from irradiation damage. However, it is usually difficult to determine the three-dimensional (3D) structure of protein complexes at the atomic level on the basis of only SANS data. To cope with this difficulty, we developed a novel approach combining 3D homology modeling with SANS profile simulation, in which whole simulated SANS profiles were examined together with experimental SANS data. We herein demonstrate the feasibilty of our strategy using proteasome activator 28 (PA28) as a model system. PA28 is a hetero-oligomeric protein composed of homologous α- and β-subunits. Although the crystal structure of the homoheptameric ring of α-subunits (PA28α7) has been reported, the physiologically relevant hetero-oligomeric structure remains to be elucidated. On the basis of the PA28α7 structure, we performed homology modeling to build hypothetical quaternary structures of the PA28 hetero-oligomer. By analyzing the SANS data of a PA28 mutant lacking a mobile loop in its α-subunit, we successfully revealed that α- and β-subunits form heteroheptameric rings, about half of which are stacked back to back to form a double-ring structure. Thus, our SANS approach provides in-depth information on the assembly states of protein subunits in aqueous solutions.

  14. Early stages of spinodal decomposition in Fe–Cr resolved by in-situ small-angle neutron scattering

    SciTech Connect

    Hörnqvist, M. Thuvander, M.; Steuwer, A.; King, S.; Odqvist, J.; Hedström, P.

    2015-02-09

    In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe–35Cr were performed at 773 and 798 K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a′{sup  }= 0.10–0.11 and a″ = 0.67–0.86). Furthermore, the method allows tracking of the high–Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773 K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a′{sup  }= 0.12–0.20 depending on the assumed mobility)

  15. Interactions between block copolymers and single-walled carbon nanotubes in aqueous solutions: a small-angle neutron scattering study.

    PubMed

    Granite, Meirav; Radulescu, Aurel; Pyckhout-Hintzen, Wim; Cohen, Yachin

    2011-01-18

    The amphiphilic copolymers of the Pluronic family are known to be excellent dispersants for single-walled carbon nanotubes (SWCNT) in water, especially F108 and F127, which have rather long end-blocks of poly(ethylene oxide) (PEO). In this study, the structure of the CNT/polymer hybrid formed in water is evaluated by measurements of small-angle neutron scattering (SANS) with contrast variation, as supported by cryo-transmission electron microscopy (cryo-TEM) imaging. The homogeneous, stable, inklike dispersions exhibited very small isolated bundles of carbon nanotubes in cryo-TEM images. SANS experiments were conducted at different D(2)O/H(2)O content of the dispersing solvent. The data for both systems showed surprisingly minimal intensity values at 70% D(2)O solvent composition, which is much higher than the expected value of 17% D(2)O that is based on the scattering length density (SLD) of PEO. At this near match point, the data exhibited a q(-1) power law relation of intensity to the scattering vector (q), indicating rodlike entities. Two models are evaluated, as extensions to Pederson's block copolymer micelles models. One is loosely adsorbed polymer chains on a rodlike CNT bundle. In the other, the hydrophobic block is considered to form a continuous hydrated shell on the CNT surface, whereas the hydrophilic blocks emanate into the solvent. Both models were found to fit the experimental data reasonably well. The model fit required special considerations of the tight association of water molecules around PEO chains and slight isotopic selectivity.

  16. A study of alcohol-induced gelation of beta-lactoglobulin with small-angle neutron scattering, neutron spin echo, and dynamic light scattering measurements.

    PubMed

    Yoshida, Koji; Yamaguchi, Toshio; Osaka, Noboru; Endo, Hitoshi; Shibayama, Mitsuhiro

    2010-04-07

    Gelation of beta-lactoglobulin (beta-Lg) in various alcohol-water mixtures with 0.1 M (M = mol L(-1)) hydrochloric acid was investigated with small-angle neutron scattering (SANS), neutron spin echo (NSE), and time-resolved dynamic light scattering (TRDLS) measurements. The beta-Lg in alcohol-water solutions undergoes gelation at specific alcohol concentrations where the alcohol-induced alpha-helical structure of beta-Lg is stabilized. The SANS profiles showed that beta-Lg exists as a single molecule at a low alcohol concentration. With increasing alcohol concentration, the profiles indicate a power law behavior of approximately 1.7 when the samples gelate. These behaviors were observed in all alcohol-water mixtures used, but the alcohol concentrations where the SANS profiles change shift to a lower alcohol concentration region with an increase in the size of the hydrophobic group of the alcohols. Apparent diffusion constants, obtained from the intermediate scattering function (ISF) of NSE and the intensity time correlation function (ITCF) of TRDLS, mainly depend on the viscosity of alcohol-water mixtures before gelation. After gelation, on the other hand, the ISFs of gels do not change appreciably in the range of the NSE time scale, indicating the microscopically rigid structure of beta-Lg gel. The ITCF functions obtained from TRDLS follow a double exponential decay type before gelation, but a logarithmic one (exponent alpha = 0.7) after gelation. It is most likely that the alcohol-induced gelation undergoes a similar mechanism to that for the heat-induced one at pH = 7 where beta-Lg aggregates stick together to form a fractal network, although the gelation time is faster in the former than in the latter.

  17. What can we learn about the lipid vesicle structure from the small-angle neutron scattering experiment?

    PubMed

    Kiselev, M A; Zemlyanaya, E V; Aswal, V K; Neubert, R H H

    2006-08-01

    Small-angle neutron scattering (SANS) on the unilamellar vesicle (ULV) populations (diameter 500 and 1,000 A) in D2O was used to characterize lipid vesicles from dimyristoylphosphatidylcholine (DMPC) at three phases: gel Lbeta', ripple Pbeta' and liquid Lalpha. Parameters of vesicle populations and internal structure of the DMPC bilayer were characterized on the basis of the separated form factor (SFF) model. Vesicle shape changes from nearly spherical in the Lalpha phase to elliptical in the Pbeta' and Lbeta' phases. This is true for vesicles prepared via extrusion through pores with the diameter 500 A. Parameters of the internal bilayer structure (thickness of the membrane and the hydrophobic core, hydration and the surface area of the lipid molecule) were determined on the basis of the hydrophobic-hydrophilic (HH) approximation of neutron scattering length density across the bilayer rhox and of the step function (SF) approximation of rhox. DMPC membrane thickness in the Lalpha phase (T = 30 degrees C) demonstrates a dependence on the membrane curvature for extruded vesicles. Prepared via extrusion through 500 A diameter pores, vesicle population in the Lalpha phase has the following characteristics: average value of minor semi-axis 266 +/- 2 A, ellipse eccentricity 1.11 +/- 0.02, polydispersity 26%, thickness of the membrane 48.9 +/- 0.2 A and of the hydrophobic core 19.9 +/- 0.4 A, surface area 60.7 +/- 0.5 A2 and number of water molecules 12.8 +/- 0.3 per DMPC molecule. Vesicles prepared via extrusion through pores with the diameter 1,000 A have polydispersity of 48% and membrane thickness of 45.5 +/- 0.6 A in the Lalpha phase. SF approximation was used to describe the DMPC membrane structure in Lbeta' (T = 10 degrees C) and Pbeta' (T = 20 degrees C) phases. Extruded DMPC vesicles in D2O have membrane thickness of 49.6 +/- 0.5 A in the Lbeta' phase and 48.3 +/- 0.6 A in the Pbeta' phase. The dependence of the DMPC membrane thickness on temperature was restored

  18. Microstructural characterization of dental zinc phosphate cements using combined small angle neutron scattering and microfocus X-ray computed tomography.

    PubMed

    Viani, Alberto; Sotiriadis, Konstantinos; Kumpová, Ivana; Mancini, Lucia; Appavou, Marie-Sousai

    2017-04-01

    To characterize the microstructure of two zinc phosphate cement formulations in order to investigate the role of liquid/solid ratio and composition of powder component, on the developed porosity and, consequently, on compressive strength. X-ray powder diffraction with the Rietveld method was used to study the phase composition of zinc oxide powder and cements. Powder component and cement microstructure were investigated with scanning electron microscopy. Small angle neutron scattering (SANS) and microfocus X-ray computed tomography (XmCT) were together employed to characterize porosity and microstructure of dental cements. Compressive strength tests were performed to evaluate their mechanical performance. The beneficial effects obtained by the addition of Al, Mg and B to modulate powder reactivity were mitigated by the crystallization of a Zn aluminate phase not involved in the cement setting reaction. Both cements showed spherical pores with a bimodal distribution at the micro/nano-scale. Pores, containing a low density gel-like phase, developed through segregation of liquid during setting. Increasing liquid/solid ratio from 0.378 to 0.571, increased both SANS and XmCT-derived specific surface area (by 56% and 22%, respectively), porosity (XmCT-derived porosity increased from 3.8% to 5.2%), the relative fraction of large pores ≥50μm, decreased compressive strength from 50±3MPa to 39±3MPa, and favored microstructural and compositional inhomogeneities. Explain aspects of powder design affecting the setting reaction and, in turn, cement performance, to help in optimizing cement formulation. The mechanism behind development of porosity and specific surface area explains mechanical performance, and processes such as erosion and fluoride release/uptake. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Microstructural characterization of dental zinc phosphate cements using combined small angle neutron scattering and microfocus X-ray computed tomography.

    PubMed

    Viani, Alberto; Sotiriadis, Konstantinos; Kumpová, Ivana; Mancini, Lucia; Appavou, Marie-Sousai

    2017-02-17

    To characterize the microstructure of two zinc phosphate cement formulations in order to investigate the role of liquid/solid ratio and composition of powder component, on the developed porosity and, consequently, on compressive strength. X-ray powder diffraction with the Rietveld method was used to study the phase composition of zinc oxide powder and cements. Powder component and cement microstructure were investigated with scanning electron microscopy. Small angle neutron scattering (SANS) and microfocus X-ray computed tomography (XmCT) were together employed to characterize porosity and microstructure of dental cements. Compressive strength tests were performed to evaluate their mechanical performance. The beneficial effects obtained by the addition of Al, Mg and B to modulate powder reactivity were mitigated by the crystallization of a Zn aluminate phase not involved in the cement setting reaction. Both cements showed spherical pores with a bimodal distribution at the micro/nano-scale. Pores, containing a low density gel-like phase, developed through segregation of liquid during setting. Increasing liquid/solid ratio from 0.378 to 0.571, increased both SANS and XmCT-derived specific surface area (by 56% and 22%, respectively), porosity (XmCT-derived porosity increased from 3.8% to 5.2%), the relative fraction of large pores ≥50μm, decreased compressive strength from 50±3MPa to 39±3MPa, and favored microstructural and compositional inhomogeneities. Explain aspects of powder design affecting the setting reaction and, in turn, cement performance, to help in optimizing cement formulation. The mechanism behind development of porosity and specific surface area explains mechanical performance, and processes such as erosion and fluoride release/uptake. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. The microstructure and morphology of carbon black: a study using small angle neutron scattering and contrast variation

    SciTech Connect

    Hjelm, R.P. Jr. ); Wampler, W.A. ); Seeger, P.A. ); Gerspacher, M. )

    1994-12-01

    This is a study of the form and structure of particles and particle aggregates of an experimental high surface area carbon black (HSA) using small-angle neutron scattering and the method of contrast variation. Contrast variation was effected by studying suspensions of the carbon black in cyclohexane containing different fractions of deutero-cyclohexane. We find that the approximately 29 nm diameter HSA particles are arranged as small, linear aggregates with average aggregation number between 4 and 6. The structure averaged over the particle population is best represented by a prolate ellipsoid of revolution with semi axes 14.5 and 76.4 nm. The surface of the aggregates appears smooth over length scales larger than 1 nm, which places an upper limit on the surface roughness observed by other methods. The internal structure of the aggregates is described by a shell-core model, with the shell density being consistent with a graphitic structure and the core being of lower density, more like amorphous carbon. Some fraction of the core volume (0.1 to 0.2) is taken up by voids that are not accessible to the solvent. An estimate of the shell thickness gives 1 to 2 nm along the ellipsoid minor axis and 6 to 10 nm along the major axis. The particles of the aggregate appear to be fused so that the less dense amorphous core is continuous through the inner parts of the aggregate. The information that can be obtained on the internal structure using contrast variation is limited by heterogeneity in the chemical composition of carbon black aggregates.

  1. Time-resolving analysis of cryotropic gelation of water/poly(vinyl alcohol) solutions via small-angle neutron scattering.

    PubMed

    Auriemma, Finizia; De Rosa, Claudio; Ricciardi, Rosa; Lo Celso, Fabrizio; Triolo, Roberto; Pipich, Vitaly

    2008-01-24

    The structural transformations occurring in initially homogeneous aqueous solutions of poly(vinyl alcohol) (PVA) through application of freezing (-13 degrees C) and thawing (20 degrees C) cycles is investigated by time resolving small-angle neutron scattering (SANS). These measurements indicate that formation of gels of complex hierarchical structure arises from occurrence of different elementary processes, involving different length and time scales. The fastest process that could be detected by our measurements during the first cryotropic treatment consists of the crystallization of the solvent. However, solvent crystallization is incomplete, and an unfrozen liquid microphase more concentrated in PVA than the initial solution is also formed. Crystallization of PVA takes place inside the unfrozen liquid microphase and is slowed down because of formation of a microgel fraction. Water crystallization takes place in the early 10 min of the treatment of the solution at subzero temperatures, and although below 0 degrees C the PVA solutions used for preparation of cryogels should be below the spinodal curve, occurrence of liquid-liquid phase separation could not be detected in our experiments. Upon thawing, ice crystals melt, and transparent gels are obtained that become opaque in approximately 200 min, due to a slow and progressive increase of the size of microheterogeneities (dilute and dense regions) imprinted during the fast freezing by the crystallization of water. During the permanence of these gels at room temperature (for hours), the presence of a high content of water (higher than 85% by mass) prevents further crystallization of PVA. Crystallization of PVA, in turn, is resumed by freezing the gels at subzero temperatures, after water crystallization and consequent formation of an unfrozen microphase. The kinetic parameters of PVA crystallization during the permanence of these gels at subzero temperatures are the same shown by PVA during the first freezing step

  2. The microstructure and morphology of carbon black: A study using small angle neutron scattering and contrast variation

    SciTech Connect

    Hjelm, R.P. Jr.; Seeger, P.A.; Wampler, W.A.; Gerspacher, M.

    1994-04-01

    This is a study of the microstructure of particles of an experimental high surface area carbon black (HSA) and of the morphology of the particle aggregates using small-angle neutron scattering and the method of contrast variation. Contrast variation was effected by studying suspensions of the carbon black in cyclohexane containing different fractions of deuterocyclohexane. We find that the approximately 29 nm diameter HSA particles are arranged as small, linear aggregates with average aggregation number between 4 and 6. The structure averaged over the particle population is best represented by a prolate ellipsoid of revolution with semi axes 14.5 and 76.4 nm. The surface of the aggregates appears smooth over length scales longer than 1 nm, which places an upper limit on the surface roughness observed by other methods. The intemal structure of the aggregates is described by a shell-core model, with the shell density being consistent with a graphitic structure and the core being of lower density, more like amorphous carbon. Some fraction of the core volume (0.1 to 0.2) is taken up by voids that are not accessible to the solvent. An estimate of the shell thickness gives 1 to 2 nm along the ellipsoid minor axis and 6 to 10 nm along the major axis. The particles of the aggregate appear to be fused so that the less dense amorphous core is continuous through the inner parts of the aggregate. The information that can be obtained on the internal structure using contrast variation is limited by nonheterogeneity in the chemical composition of carbon black aggregates.

  3. Structural studies of agar-gelatin complex coacervates by small angle neutron scattering, rheology and differential scanning calorimetry.

    PubMed

    Singh, S Santinath; Aswal, V K; Bohidar, H B

    2007-08-01

    Agar-gelatin complex coacervates are studied by small angle neutron scattering (SANS), rheology (in both flow and temperature scan modes) and differential scanning calorimetry (DSC) in order to probe the microscopic structure of this dense protein-polysaccharide-rich phase. DSC and isochronal temperature sweep (rheology) experiments yielded a characteristic temperature at approximately 35+/-2 degrees C. Rheology data revealed a second characteristic temperature at approximately 75+/-5 degrees C which was absent in DSC thermograms. In the flow mode, shear viscosity (eta) was found to scale with (Carreau model) applied shear rate (gamma ) as: eta(gamma ) approximately (gamma )(-k) with k=1.2+/-0.2 indicating non-Newtonian and shear-thinning features independent of ionic strength. The static structure factor S(q) deduced from SANS data in the low wave vector (0.018 A(-1)

  4. Quality assessment of neutron delivery system for small-angle neutron scattering diffractometers of the Jülich Centre for Neutron Science at the FRM II

    NASA Astrophysics Data System (ADS)

    Radulescu, Aurel; Pipich, Vitaliy; Ioffe, Alexander

    2012-10-01

    Following the shutdown of FRJ-2 research reactor in Jülich, the pinhole small-angle neutron diffractometers KWS-1 and KWS-2 have been moved to the research reactor FRM II in Garching. The installation of these 40 m long instruments required the design and setup of new neutron guides with geometrical and optical features imposed by the instruments' positioning in the neutron guide hall, such as, the predetermined length and beam height as well as the foreseen improvement of the instrument performance. We report here about the quality assessment of the newly constructed neutron guides with respect to the optical, geometrical and alignment characteristics and the positioning of the velocity selector integrated in the neutron guide system by comparing the features of the measured neutron beams (in terms of neutron flux, intensity distribution and beam profile) with the results of the simulations of optimal neutron guide systems.

  5. Non-destructive analysis of hydrogen-induced cracking of api steels using acoustic microscopy and small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Oh, S. B.; Choi, Y.; Jung, H. G.; Kho, S. W.; Lee, C. S.

    2014-12-01

    Acoustic microscopy and small-angle neutron scattering were applied to non-destructively evaluate the hydrogen-induced cracking of API steels and to find the initiation time of the crack. The API steels had equiaxed grains with about 4 to 12-μm average grain size along the rolling, sample-normal, and transverse directions. For 5 days of immersion in a sodium-acetic solution with chloride ions (NaCl: CH3COOH: H2O: FeCl2 = 50: 5: 944: 1, pH = 2.7), micro-sized cracks were not formed in the as-received specimen, but they did form in the 7% deformed specimen. Nano-sized cracks were observed in the specimen after 3 days of immersion by small-angle neutron scattering.

  6. Small-angle neutron scattering study of the structure of mixed micellar solutions based on heptaethylene glycol monotetradecyl ether and cesium dodecyl sulfate

    SciTech Connect

    Rajewska, A.; Medrzycka, K.; Hallmann, E.; Soloviov, D. V.

    2016-01-15

    The micellization in mixed aqueous systems based on a nonionic surfactant, heptaethylene glycol monotetradecyl ether (C{sub 14}E{sub 7}), and an anionic surfactant, cesium dodecyl sulfate, has been investigated by small-angle neutron scattering. Preliminary data on the behavior of the C{sub 14}E{sub 7} aqueous solutions (with three concentrations, 0.17, 0.5, and 1%) mixed with a small amount of anionic surfactant, cesium dodecyl sulfate, are reported.

  7. A study of the structure of mixed micellar solutions based on heptaethylene glycol monotetradecyl ether and sodium (lithium) dodecyl sulfate by the small-angle neutron scattering method

    NASA Astrophysics Data System (ADS)

    Rajewska, A.; Medrzycka, K.; Hallmann, E.

    2007-09-01

    The micellization in mixed aqueous systems based on a new nonionic surfactant, namely, heptaethylene glycol monotetradecyl ether (C14E7), and an anionic surfactant, namely, sodium dodecyl sulfate, sodium decyl sulfate, or lithium dodecyl sulfate, is studied by small-angle neutron scattering. Preliminary results of the investigation into the behavior of C14E7 aqueous solutions (at two concentrations, 0.17 and 0.50%) upon addition of small amounts of three different classical anionic surfactants are reported.

  8. Scattering Density Profile Model of POPG Bilayers as Determined by Molecular Dynamics Simulations and Small-Angle Neutron and X-ray Scattering Experiments

    SciTech Connect

    Kucerka, Norbert; Holland, B; Gray, C.G; Tomberli, B; Katsaras, John

    2012-01-01

    We combine molecular dynamics (MD) simulations and experiment, both small-angle neutron (SANS) and small-angle X-ray scattering (SAXS), to determine the precise structure of bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG), a lipid commonly encountered in bacterial membranes. Experiment and simulation are used to develop a one-dimensional scattering density profile (SDP) model suitable for the analysis of experimental data. The joint refinement of such data (i.e., SANS and SAXS) results in the area per lipid that is then used in the fixed-area simulations. In the final step, the direct comparison of simulated-to-experimental data gives rise to the detailed structure of POPG bilayers. From these studies we conclude that POPG s molecular area is 66.0 +/- 1.3 ^2, its overall bilayer thickness is 36.7 +/- 0.7 , and its hydrocarbon region thickness is 27.9 ( 0.6 , assuming a simulated value of 1203 ^3 for the total lipid volume.

  9. Water-in-model oil emulsions studied by small-angle neutron scattering: interfacial film thickness and composition.

    PubMed

    Verruto, Vincent J; Kilpatrick, Peter K

    2008-11-18

    The ever-increasing worldwide demand for energy has led to the upgrading of heavy crude oil and asphaltene-rich feedstocks becoming viable refining options for the petroleum industry. Traditional problems associated with these feedstocks, particularly stable water-in-petroleum emulsions, are drawing increasing attention. Despite considerable research on the interfacial assembly of asphaltenes, resins, and naphthenic acids, much about the resulting interfacial films is not well understood. Here, we describe the use of small-angle neutron scattering (SANS) to elucidate interfacial film properties from model emulsion systems. Modeling the SANS data with both a polydisperse core/shell form factor as well as a thin sheet approximation, we have deduced the film thickness and the asphaltenic composition within the stabilizing interfacial films of water-in-model oil emulsions prepared in toluene, decalin, and 1-methylnaphthalene. Film thicknesses were found to be 100-110 A with little deviation among the three solvents. By contrast, asphaltene composition in the film varied significantly, with decalin leading to the most asphaltene-rich films (30% by volume of the film), while emulsions made in toluene and methylnaphthalene resulted in lower asphaltenic contents (12-15%). Through centrifugation and dilatational rheology, we found that trends of decreasing water resolution (i.e., increasing emulsion stability) and increasing long-time dilatational elasticity corresponded with increasing asphaltene composition in the film. In addition to the asphaltenic composition of the films, here we also deduce the film solvent and water content. Our analyses indicate that 1:1 (O/W) emulsions prepared with 3% (w/w) asphaltenes in toluene and 1 wt % NaCl aqueous solutions at pH 7 and pH 10 resulted in 80-90 A thick films, interfacial areas around 2600-3100 cm (2)/mL, and films that were roughly 25% (v/v) asphaltenic, 60-70% toluene, and 8-12% water. The increased asphaltene and water film

  10. Application of small-angle neutron scattering to the study of forces between magnetically chained monodisperse ferrofluid emulsion droplets

    SciTech Connect

    Jain, Dr Nirmesh; Liu, Dr C K; Hawkett, Dr B. S.; Warr, G. G.; Hamilton, William A

    2014-01-01

    The optical magnetic chaining technique (MCT) developed by Leal-Calderon, Bibette and co-workers in the 1990 s allows precise measurements of force profiles between droplets in monodisperse ferrofluid emulsions. However, the method lacks an in-situ determination of droplet size and therefore requires the combination of separately acquired measurements of droplet chain periodicity versus an applied magnetic field from optical Bragg scattering and droplet diameter inferred from dynamic light scattering (DLS) to recover surface force-distance profiles between the colloidal particles. Compound refractive lens (CRL) focussed small-angle scattering (SANS) MCT should result in more consistent measurements of droplet size (form factor measurements in the absence of field) and droplet chaining period (from structure factor peaks when the magnetic field is applied); and, with access to shorter length scales, extend force measurements to closer approaches than possible by optical measurements. We report on CRL-SANS measurements of monodisperse ferrofluid emulsion droplets aligned in straight chains by an applied field perpendicular to the incident beam direction. Analysis of the scattering from the closely spaced droplets required algorithms that carefully treated resolution and its effect on mean scattering vector magnitudes in order to determine droplet size and chain periods to sufficient accuracy. At lower applied fields scattering patterns indicate structural correlations transverse to the magnetic field direction due to the formation of intermediate structures in early chain growth.

  11. A portable hydro-thermo-mechanical loading cell for in-situ small angle neutron scattering studies of proton exchange membranes

    SciTech Connect

    Yu, Dunji; An, Ke; Gao, Carrie Y; Heller, William T; Chen, Xu

    2013-01-01

    A portable hydro-thermo-mechanical loading cell has been designed to enable in-situ small angle neutron scattering (SANS) studies of proton exchange membranes (PEM) under immersed tensile loadings at different temperatures. The cell consists of three main parts as follows: a letter-paper-size motor-driven mechanical load frame, a SANS friendly reservoir that provides stable immersed and thermal sample conditions, and a data acquisition & control system. The ex-situ tensile tests of Nafion 212 membranes demonstrated a satisfactory thermo-mechanical testing performance of the cell for either dry or immersed conditions at elevated temperatures. The in-situ SANS tensile measurements on the Nafion 212 membranes immersed in D2O at 70oC proved the feasibility and capability of the cell for small angle scattering study on deformation behaviors of PEM and other polymer materials under hydro-thermo-mechanical loading.

  12. Microphase Separation in Pr0.67Ca0.33MnO3 by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Simon, Ch.; Mercone, S.; Guiblin, N.; Martin, C.; Brûlet, A.; André, G.

    2002-10-01

    We have evidenced by small-angle neutron scattering at low temperature the coexistence of ferromagnetism (F) and antiferromagnetism (AF) in Pr0.67Ca0.33MnO3. The results are compared to those obtained in Pr0.80Ca0.20MnO3 and Pr0.63Ca0.37MnO3, which are F and AF, respectively. Quantitative analysis shows that the small-angle scattering is not due to a mesoscopic mixing but to a nanoscopic electronic and magnetic ``red cabbage'' structure, in which the ferromagnetic phase exists in the form of thin layers in the AF matrix (stripes or 2D ``sheets'').

  13. Microstructural investigation, using small-angle neutron scattering (SANS), of Optifer steel after low dose neutron irradiation and subsequent high temperature tempering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Lindau, R.; Magnani, M.; May, R. P.; Möslang, A.; Valli, M.

    2007-08-01

    The microstructural effect of low dose neutron irradiation and subsequent high temperature tempering in the reduced activation ferritic/martensitic steel Optifer (9.3 Cr, 0.1 C, 0.50 Mn, 0.26 V, 0.96 W, 0.66 Ta, Fe bal wt%) has been studied using small-angle neutron scattering (SANS). The investigated Optifer samples had been neutron irradiated, at 250 °C, to dose levels of 0.8 dpa and 2.4 dpa. Some of them underwent 2 h tempering at 770 °C after the irradiation. The SANS measurements were carried out at the D22 instrument of the High Flux Reactor at the Institut Max von Laue - Paul Langevin, Grenoble, France. The differences observed in nuclear and magnetic SANS cross-sections after subtraction of the reference sample from the irradiated one suggest that the irradiation and the subsequent post-irradiation tempering produce the growth of non-magnetic defects, tentatively identified as microvoids.

  14. Accessible length scale of the in-plane structure in polarized neutron off-specular and grazing-incidence small-angle scattering measurements

    NASA Astrophysics Data System (ADS)

    Maruyama, R.; Bigault, T.; Wildes, A. R.; Dewhurst, C. D.; Saerbeck, T.; Honecker, D.; Yamazaki, D.; Soyama, K.; Courtois, P.

    2017-06-01

    Polarized neutron off-specular and grazing-incidence small-angle scattering measurements are useful methods to investigate the in-plane structure and its correlation of layered systems. Although these measurements give information on complementary and overlapping length scale, the different characteristics between them need to be taken into account when performed. In this study, the difference in the accessible length scale of the in-plane structure, which is one of the most important characteristics, was discussed using an Fe/Si multilayer together with simulations based on the distorted wave Born approximation.

  15. SANS study on the effect of lanthanide ions and charged lipids on the morphology of phospholipid mixtures. Small-angle neutron scattering.

    PubMed Central

    Nieh, Mu-Ping; Glinka, Charles J; Krueger, Susan; Prosser, R Scott; Katsaras, John

    2002-01-01

    The structural phase behavior of phospholipid mixtures consisting of short-chain (dihexanoyl phosphatidylcholine) and long-chain lipids (dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol), with and without lanthanide ions was investigated by small-angle neutron scattering (SANS). SANS profiles were obtained from 10 degrees C to 55 degrees C using lipid concentrations ranging from 0.0025 g/ml to 0.25 g/ml. The results reveal a wealth of distinct morphologies, including lamellae, multi-lamellar vesicles, unilamellar vesicles, and bicellar disks. PMID:11964236

  16. Small-angle neutron scattering study of structure and interaction during salt-induced liquid-liquid phase transition in protein solutions

    NASA Astrophysics Data System (ADS)

    Chinchalikar, A. J.; Aswal, V. K.; Kohlbrecher, J.; Wagh, A. G.

    2013-06-01

    The liquid-liquid phase transition (LLPT) in aqueous salt solutions of lysozyme protein has been studied by small-angle neutron scattering. Measurements have been carried out on fixed protein concentration with varying salt concentration approaching LLPT. The data are fitted considering protein interaction by the two Yukawa (2Y) potential which combines short-range attraction and long-range repulsion. We show that LLPT arises because of enhancement of non-DLVO (Derjaguin-Landau-Verwey-Overbeek) short-range attraction without any conformational structural change of the protein. The salt concentration required for LLPT as well as corresponding short-range attraction decreases significantly with increase in protein concentration.

  17. Small angle neutron scattering on an absolute intensity scale and the internal surface of diatom frustules from three species of differing morphologies.

    PubMed

    Garvey, C J; Strobl, M; Percot, A; Saroun, J; Haug, J; Vyverman, W; Chepurnov, V A; Ferris, J M

    2013-05-01

    The internal nanostructure of the diatoms Cyclotella meneghiniana, Seminavis robusta and Achnanthes subsessilis was investigated using small angle neutron scattering (SANS) to examine thin biosilica samples, consisting of isotropic (powder) from their isolated cell walls. The interpretation of SANS data was assisted by several other measurements. The N2 adsorption, interpreted within the Branuer-Emmet-Teller isotherm, yielded the specific surface area of the material. Fourier transform infrared (FTIR) and Raman spectroscopy indicates that the isolated material is amorphous silica with small amounts of organic cell wall materials acting as a filling material between the silica particles. A two-phase (air and amorphous silica) model was used to interpret small angle neutron scattering data. After correction for instrumental resolution, the measurements on two SANS instruments covered an extended range of scattering vectors 0.0011 nm(-1) < q < 5.6 nm(-1), giving an almost continuous SANS curve over a range of scattering vectors, q, on an absolute scale of intensity for each sample. Each of the samples gave a characteristic scattering curve where log (intensity) versus log (q) has a -4 dependence, with other features superimposed. In the high-q regime, departure from this behaviour was observed at a length-scales equivalent to the proposed unitary silica particle. The limiting Porod scattering law was used to determine the specific area per unit of volume of each sample illuminated by the neutron beam. The Porod behaviour, and divergence from this behaviour, is discussed in terms of various structural features and the proposed mechanisms for the bio-assembly of unitary silica particles in frustules.

  18. Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation

    DOE PAGES

    White, Claire E.; Olds, Daniel P.; Hartl, Monika; ...

    2017-02-01

    The long-term durability of cement-based materials is influenced by the pore structure and associated permeability at the sub-micrometre length scale. With the emergence of new types of sustainable cements in recent decades, there is a pressing need to be able to predict the durability of these new materials, and therefore nondestructive experimental techniques capable of characterizing the evolution of the pore structure are increasingly crucial for investigating cement durability. Here, small-angle neutron scattering is used to analyze the evolution of the pore structure in alkali-activated materials over the initial 24 h of reaction in order to assess the characteristic poremore » sizes that emerge during these short time scales. By using a unified fitting approach for data modeling, information on the pore size and surface roughness is obtained for a variety of precursor chemistries and morphologies (metakaolin- and slag-based pastes). Furthermore, the impact of activator chemistry is elucidatedviathe analysis of pastes synthesized using hydroxide- and silicate-based activators. It is found that the main aspect influencing the size of pores that are accessible using small-angle neutron scattering analysis (approximately 10–500 Å in diameter) is the availability of free silica in the activating solution, which leads to a more refined pore structure with smaller average pore size. Furthermore, as the reaction progresses the gel pores visible using this scattering technique are seen to increase in size.« less

  19. Small Angle X-Ray Scattering Detector

    SciTech Connect

    Hessler, Jan P.

    2004-06-15

    A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., qmax/qmin approx=lO0.

  20. Sapphire-anvil cell for small-angle neutron scattering measurements in large-volume liquid samples up to 530 MPa

    NASA Astrophysics Data System (ADS)

    Bonetti, M.; Calmettes, P.

    2005-04-01

    A cell with unsupported beveled sapphire-anvils was developed to carry out small-angle neutron scattering measurements in large-volume liquid samples up to a pressure of 530 MPa. The body of the anvil is a cylinder with a 30 mm diameter. One end is shaped into a truncated cone with a face 14 mm in diameter. The two opposed anvils squeeze a flat metallic gasket of thickness between 1 and 3 mm with a central hole between 4 and 10 mm in diameter. The initial sample volume varies from about 10 to 240mm3. The highest achievable pressure depends on the dimensions and on the mechanical properties of the gasket. To allow a high neutron transmission of the collimated neutron beam, a 10-mm-diam bore is machined along the cell axis. For a neutron beam of 7 mm in diameter, the maximum forward scattering angle is about 9.5°. With a neutron wavelength of 0.4 nm, this allows scattering spectra to be recorded for wave-number transfers up to 2.6nm-1.

  1. Structural changes during the unfolding of Bovine serum albumin in the presence of urea: A small-angle neutron scattering study

    NASA Astrophysics Data System (ADS)

    Das, Amit; Chitra, R.; Choudhury, R. R.; Ramanadham, M.

    2004-08-01

    The native form of serum albumin is the most important soluble protein in the body plasma. In order to investigate the structural changes of Bovine serum albumin (BSA) during its unfolding in the presence of urea, a small-angle neutron scattering (SANS) study was performed. The scattering curves of dilute solutions of BSA with different concentrations of urea in D2O at pH 7.2+/-0.2 were measured at room temperature. The scattering profile was fitted to a prolate ellipsoidal shape (a, b, b) of the protein with a = 52.2 Å and b = 24.2 Å. The change in the dimensions of the protein as it unfolds was found to be anisotropic. The radius of gyration of the compact form of the protein in solution decreased as the urea concentration was increased.

  2. Fetuin-A is a mineral carrier protein: small angle neutron scattering provides new insight on Fetuin-A controlled calcification inhibition.

    PubMed

    Heiss, Alexander; Pipich, Vitaliy; Jahnen-Dechent, Willi; Schwahn, Dietmar

    2010-12-15

    Clinical studies and animal experiments have shown that the serum protein fetuin-A is a highly effective inhibitor of soft tissue calcification. This inhibition mechanism was elucidated on the basis of an in vitro fetuin-A-mineral model system. In a previous study, we found that in a two-stage process ∼100-nm sized calciprotein particles (CPPs) were formed whose final stage was stabilized by a compact outer fetuin-A monolayer against further growth. Quantitative small-angle neutron scattering data analysis revealed that even at a fetuin-A concentration close to the stability limit, only approximately one-half of the mineral ions and only 5% of the fetuin-A were contained in the CPPs. To uncover the interplay of the remaining supersaturated mineral ion fraction and of the 95% non-CPP fetuin-A, we explored the fetuin-A monomer fraction in solution by contrast variation small-angle neutron scattering. Our results suggest that the mineral ions coalesce to subnanometer-sized clusters, reminiscent of Posner clusters, which are stabilized by fetuin-A monomers. Hence, our experiments revealed a second mechanism of long-term mineral ion stabilization by the fetuin-A that is complementary to the formation of CPPs. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  3. Assessment of firing conditions in old fired-clay bricks: The contribution of X-ray powder diffraction with the Rietveld method and small angle neutron scattering

    SciTech Connect

    Viani, Alberto; Sotiriadis, Konstantinos; Len, Adél; Šašek, Petr; Ševčík, Radek

    2016-06-15

    Full characterization of fired-clay bricks is crucial for the improvement of process variables in manufacturing and, in case of old bricks, for restoration/replacement purposes. To this aim, five bricks produced in a plant in Czech Republic in the past have been investigated with a combination of analytical techniques in order to derive information on the firing process. An additional old brick from another brickyard was also used to study the influence of different raw materials on sample microstructure. The potential of X-ray diffraction with the Rietveld method and small angle neutron scattering technique has been exploited to describe the phase transformations taking place during firing and characterize the brick microstructure. Unit-cell parameter of spinel and amount of hematite are proposed as indicators of the maximum firing temperature, although for the latter, limited to bricks produced from the same raw material. The fractal quality of the surface area of pores obtained from small angle neutron scattering is also suggested as a method to distinguish between bricks produced from different raw clays. - Highlights: • Rietveld method helps in describing microstructure and physical properties of bricks. • XRPD derived cell parameter of spinel is proposed as an indicator of firing temperature. • SANS effectively describes brick micro and nanostructure, including closed porosity. • Fractal quality of pore surface is proposed as ‘fingerprint’ of brick manufacturing.

  4. Fetuin-A Is a Mineral Carrier Protein: Small Angle Neutron Scattering Provides New Insight on Fetuin-A Controlled Calcification Inhibition

    PubMed Central

    Heiss, Alexander; Pipich, Vitaliy; Jahnen-Dechent, Willi; Schwahn, Dietmar

    2010-01-01

    Clinical studies and animal experiments have shown that the serum protein fetuin-A is a highly effective inhibitor of soft tissue calcification. This inhibition mechanism was elucidated on the basis of an in vitro fetuin-A-mineral model system. In a previous study, we found that in a two-stage process ∼100-nm sized calciprotein particles (CPPs) were formed whose final stage was stabilized by a compact outer fetuin-A monolayer against further growth. Quantitative small-angle neutron scattering data analysis revealed that even at a fetuin-A concentration close to the stability limit, only approximately one-half of the mineral ions and only 5% of the fetuin-A were contained in the CPPs. To uncover the interplay of the remaining supersaturated mineral ion fraction and of the 95% non-CPP fetuin-A, we explored the fetuin-A monomer fraction in solution by contrast variation small-angle neutron scattering. Our results suggest that the mineral ions coalesce to subnanometer-sized clusters, reminiscent of Posner clusters, which are stabilized by fetuin-A monomers. Hence, our experiments revealed a second mechanism of long-term mineral ion stabilization by the fetuin-A that is complementary to the formation of CPPs. PMID:21156141

  5. Digenetic Changes in Macro- to Nano-Scale Porosity in the St. Peter Sandstone:L An (Ultra) Small Angle Neutron Scattering and Backscattered Electron Imagining Analysis

    SciTech Connect

    Anovitz, Lawrence {Larry} M; Cole, David; Rother, Gernot; Allard Jr, Lawrence Frederick; Jackson, Andrew; Littrell, Ken

    2013-01-01

    Small- and Ultra-Small Angle Neutron Scattering (SANS and USANS) provide powerful tools for quantitative analysis of porous rocks, yielding bulk statistical information over a wide range of length scales. This study utilized (U)SANS to characterize shallowly buried quartz arenites from the St. Peter Sandstone. Backscattered electron imaging was also used to extend the data to larger scales. These samples contain significant volumes of large-scale porosity, modified by quartz overgrowths, and neutron scattering results show significant sub-micron porosity. While previous scattering data from sandstones suggest scattering is dominated by surface fractal behavior over many orders of magnitude, careful analysis of our data shows both fractal and pseudo-fractal behavior. The scattering curves are composed of subtle steps, modeled as polydispersed assemblages of pores with log-normal distributions. However, in some samples an additional surface-fractal overprint is present, while in others there is no such structure, and scattering can be explained by summation of non-fractal structures. Combined with our work on other rock-types, these data suggest that microporosity is more prevalent, and may play a much more important role than previously thought in fluid/rock interactions.

  6. Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

    NASA Astrophysics Data System (ADS)

    Schmiele, Martin; Schindler, Torben; Unruh, Tobias; Busch, Sebastian; Morhenn, Humphrey; Westermann, Martin; Steiniger, Frank; Radulescu, Aurel; Lindner, Peter; Schweins, Ralf; Boesecke, Peter

    2013-06-01

    Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr.JACGAR0021-889810.1107/S0021889807044378 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

  7. Feasibility and applications of the spin-echo modulation option for a small angle neutron scattering instrument at the European Spallation Source

    NASA Astrophysics Data System (ADS)

    Kusmin, A.; Bouwman, W. G.; van Well, A. A.; Pappas, C.

    2017-06-01

    We describe theoretical and practical aspects of spin-echo modulated small-angle neutron scattering (SEMSANS) as well as the potential combination with SANS. Based on the preliminary technical designs of SKADI (a SANS instrument proposed for the European Spallation Source) and a SEMSANS add-on, we assess the practicability, feasibility and scientific merit of a combined SANS and SEMSANS setup by calculating tentative SANS and SEMSANS results for soft matter, geology and advanced material samples that have been previously studied by scattering methods. We conclude that lengths from 1 nm up to 0.01 mm can be observed simultaneously in a single measurement. Thus, the combination of SANS and SEMSANS instrument is suited for the simultaneous observation of a wide range of length scales, e.g. for time-resolved studies of kinetic processes in complex multiscale systems.

  8. On structural features of fullerene C60 dissolved in carbon disulfide: Complementary study by small-angle neutron scattering and molecular dynamic simulations

    NASA Astrophysics Data System (ADS)

    Avdeev, M. V.; Tropin, T. V.; Bodnarchuk, I. A.; Yaradaikin, S. P.; Rosta, L.; Aksenov, V. L.; Bulavin, L. A.

    2010-04-01

    The parameters of fullerene C60 dissolved in carbon disulfide CS2 are analyzed by small-angle neutron scattering (SANS) in a wide interval of momentum transfer. To exclude the influence of nonequilibrium conditions, the solutions are prepared without applying shaking, stirring or ultrasound. No indication of the equilibrium cluster state of C60 (with the cluster size below 60 nm) in the final solutions is revealed. Molecular dynamic simulations are complementary used to find out the partial volume of C60 in CS2 and the scattering contribution of the solvent organization at the interface with the fullerene molecule, which is shown to be small. Among several approaches for describing SANS data the preference is given to the model, which takes into account the presence of stable C60 dimers (comprising 10% of the total particle number density) in the solution.

  9. On the microstructure of organic solutions of mono-carboxylic acids: Combined study by infrared spectroscopy, small-angle neutron scattering and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Eremin, Roman A.; Kholmurodov, Kholmirzo T.; Petrenko, Viktor I.; Rosta, László; Grigoryeva, Natalia A.; Avdeev, Mikhail V.

    2015-11-01

    The data of infrared spectroscopy (IR), molecular dynamics (MD) simulations and small-angle neutron scattering (SANS) have been combined to conclude about the nanoscale structural organization of organic non-polar solutions of saturated mono-carboxylic acids with different alkyl chain lengths for diluted solutions of saturated myristic (C14) and stearic (C18) acids in benzene and decalin. In particular, the degree of dimerization was found from the IR spectra. The structural anisotropy of the acids and their dimers was used in the treatment of the data of MD simulations to describe the solute-solvent interface in a cylindrical approximation and show its rather strong influence on SANS. The corresponding scattering length density profiles were used to fit the experimental SANS data comprising the information about the acid molecule isomerization. The SANS data from concentrated solutions showed a partial self-assembling of the acids within the nematic transition is different for two solvents due to lyophobic peculiarities.

  10. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

    SciTech Connect

    Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; Mastalerz, Maria; Schimmelmann, Arndt

    2014-12-17

    We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of the polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.

  11. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

    DOE PAGES

    Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; ...

    2014-12-17

    We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of themore » polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.« less

  12. Small-angle neutron scattering from aqueous dispersions of single-walled carbon nanotubes with pluronic F127 and poly(vinylpyrrolidone).

    PubMed

    Granite, Meirav; Radulescu, Aurel; Cohen, Yachin

    2012-07-31

    Amphiphilic block copolymers are excellent dispersants for single-walled carbon nanotubes (SWCNT) in aqueous environments, where their noncovalent attachments do not affect the π chemical bonding. In this small-angle neutron scattering (SANS) study, we investigate whether the coverage of Pluronic F127 polymers around the CNTs depends on the solution concentration in the range of 1-6% (w/w). The observations indicate that at these concentrations the SWCNT surface is fully saturated at about 14 chains per unit length of 100 Å. Furthermore, we seek to verify whether the unusual effect observed in a previous study by contrast variation, interpreted as being due to a dense hydration layer around the polymer chains, also appears using a homopolymer (polyvinylpyrrolidone - PVP) that does not contain poly(ethylene oxide) (PEO) units. The SANS patterns showed again a minimal intensity value at much higher solvent composition (75% D(2)O) than the expected value of 29% D(2)O. The minimum scattering curve exhibited a nearly q(-1) power law at small angles, an indication of rodlike entities. A model of a CNT thin bundle with loosely adsorbed polymer chains around it (core-chains) was reasonably well fitted to the data. The polymer chains are assumed to be surrounded by a water layer with a slightly higher density than bulk water, having partial selectivity for D(2)O.

  13. Microstructural changes of globules in calcium-silicate-hydrate gels with and without additives determined by small-angle neutron and X-ray scattering.

    PubMed

    Chiang, Wei-Shan; Fratini, Emiliano; Ridi, Francesca; Lim, Sung-Hwan; Yeh, Yi-Qi; Baglioni, Piero; Choi, Sung-Min; Jeng, U-Ser; Chen, Sow-Hsin

    2013-05-15

    The microstructure of calcium-silicate-hydrate (C-S-H) gel, a major hydrated phase of Ordinary Portland Cement, with and without polycarboxylic ether (PCE) additives is investigated by combined analyses of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) data. The results show that these comb-shaped polymers tend to increase the size of the disk-like globules but have little influence on the thickness of the water and calcium silicate layers within the globules. As a result, the fractal packing of the globules becomes more open in the range of a few hundred nanometers, in the sense that the mass fractal dimension diminishes, since the PCE adsorption on the globules increases the repulsive force between and polydispersity of the C-S-H units. Moreover, scanning electron microscope (SEM) study of the synthesized C-S-H gels in the micrometer range shows that the PCEs depress the formation of fibrils while enhancing the foil-like morphology.

  14. Small-angle scattering and 3D structure interpretation.

    PubMed

    Trewhella, Jill

    2016-10-01

    This review focuses on advances in the application of solution small-angle scattering (SAS) in structural analysis of biomolecules and the complexes they form. Examples highlighted illustrate the unique contribution of SAS, using both X-rays and neutrons, in hybrid or integrative modelling methods. The increased information content when neutron scattering with contrast variation is used is a particular focus. Finally, progress toward an agreed reporting framework, the development of open data and model archives, and the importance of these initiatives is covered.

  15. Density minimum of confined water at low temperatures: a combined study by small-angle scattering of X-rays and neutrons.

    PubMed

    Erko, M; Wallacher, D; Hoell, A; Hauss, T; Zizak, I; Paris, O

    2012-03-21

    A simple explanation is given for the low-temperature density minimum of water confined within cylindrical pores of ordered nanoporous materials of different pore size. The experimental evidence is based on combined data from in-situ small-angle scattering of X-rays (SAXS) and neutrons (SANS), corroborated by additional wide-angle X-ray scattering (WAXS). The combined scattering data cannot be described by a homogeneous density distribution of water within the pores, as was originally suggested from SANS data alone. A two-step density model reveals a wall layer covering approximately two layers of water molecules with higher density than the residual core water in the central part of the pores. The temperature-induced changes of the scattering signal from both X-rays and neutrons are consistent with a minimum of the average water density. We show that the temperature at which this minimum occurs depends monotonically on the pore size. Therefore we attribute this minimum to a liquid-solid transition of water influenced by confinement. For water confined in the smallest pores of only 2 nm in diameter, the density minimum is explained in terms of a structural transition of the surface water layer closest to the hydrophilic pore walls.

  16. Small Angle X-Ray Scattering Detector

    DOEpatents

    Hessler, Jan P.

    2004-06-15

    A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., q.sub.max /q.sub.min.congruent.100.

  17. Small-Angle Neutron Scattering Studies on the Multilamellae Formed by Mixing Lamella-Forming Cationic Diblock Copolymers with Lipids and Their Interaction with DNA.

    PubMed

    Yang, Po-Wei; Lin, Tsang-Lang; Liu, I-Ting; Hu, Yuan; Jeng, U-Ser; Gilbert, Elliot Paul

    2016-02-23

    We demonstrate that the lamella-forming polystyrene-block-poly(N-methyl-4-vinylpyridinium iodine) (PS-b-P4VPQ), with similar sizes of the PS and P4VPQ blocks, can be dispersed in the aqueous solutions by forming lipid/PS-b-P4VPQ multilamellae. Using small-angle neutron scattering (SANS) and 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (d62-DPPC) in D2O, a broad correlation peak is found in the scattering profile that signifies the formation of the loosely ordered d62-DPPC/PS-b-P4VPQ multilamellae. The thicknesses of the hydrophobic and hydrophilic layers of the d62-DPPC/PS-b-P4VPQ multilamellae are close to the PS layer and the condensed brush layer thicknesses as determined from previous neutron reflectometry studies on the PS-b-P4VPQ monolayer at the air-water interface. Such well-dispersed d62-DPPC/PS-b-P4VPQ multilamellae are capable of forming multilamellae with DNA in aqueous solution. It is found that the encapsulation of DNA in the hydrophilic layer of the d62-DPPC/PS-b-P4VPQ multilamellae slightly increases the thickness of the hydrophilic layer. Adding CaCl2 can enhance the DNA adsorption in the hydrophilic brush layer, and it is similar to that observed in the neutron reflectometry study of the DNA adsorption by the PS-b-P4VPQ monolayer.

  18. Emerging applications of small angle solution scattering in structural biology.

    PubMed

    Chaudhuri, Barnali N

    2015-03-01

    Small angle solution X-ray and neutron scattering recently resurfaced as powerful tools to address an array of biological problems including folding, intrinsic disorder, conformational transitions, macromolecular crowding, and self or hetero-assembling of biomacromolecules. In addition, small angle solution scattering complements crystallography, nuclear magnetic resonance spectroscopy, and other structural methods to aid in the structure determinations of multidomain or multicomponent proteins or nucleoprotein assemblies. Neutron scattering with hydrogen/deuterium contrast variation, or X-ray scattering with sucrose contrast variation to a certain extent, is a convenient tool for characterizing the organizations of two-component systems such as a nucleoprotein or a lipid-protein assembly. Time-resolved small and wide-angle solution scattering to study biological processes in real time, and the use of localized heavy-atom labeling and anomalous solution scattering for applications as FRET-like molecular rulers, are amongst promising newer developments. Despite the challenges in data analysis and interpretation, these X-ray/neutron solution scattering based approaches hold great promise for understanding a wide variety of complex processes prevalent in the biological milieu.

  19. Emerging applications of small angle solution scattering in structural biology

    PubMed Central

    Chaudhuri, Barnali N

    2015-01-01

    Small angle solution X-ray and neutron scattering recently resurfaced as powerful tools to address an array of biological problems including folding, intrinsic disorder, conformational transitions, macromolecular crowding, and self or hetero-assembling of biomacromolecules. In addition, small angle solution scattering complements crystallography, nuclear magnetic resonance spectroscopy, and other structural methods to aid in the structure determinations of multidomain or multicomponent proteins or nucleoprotein assemblies. Neutron scattering with hydrogen/deuterium contrast variation, or X-ray scattering with sucrose contrast variation to a certain extent, is a convenient tool for characterizing the organizations of two-component systems such as a nucleoprotein or a lipid-protein assembly. Time-resolved small and wide-angle solution scattering to study biological processes in real time, and the use of localized heavy-atom labeling and anomalous solution scattering for applications as FRET-like molecular rulers, are amongst promising newer developments. Despite the challenges in data analysis and interpretation, these X-ray/neutron solution scattering based approaches hold great promise for understanding a wide variety of complex processes prevalent in the biological milieu. PMID:25516491

  20. Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

    SciTech Connect

    Saito, Kotaro Ono, Kanta; Ueno, Tetsuro; Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira; Harada, Masashi; Keiderling, Uwe

    2015-05-07

    The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd{sub 2}Fe{sub 14}B grains.

  1. Characterization of white poplar and eucalyptus after ionic liquid pretreatment as a function of biomass loading using X-ray diffraction and small angle neutron scattering.

    PubMed

    Yuan, Xueming; Duan, Yonghao; He, Lilin; Singh, Seema; Simmons, Blake; Cheng, Gang

    2017-05-01

    A systematic study was performed to understand interactions among biomass loading during ionic liquid (IL) pretreatment, biomass type and biomass structures. White poplar and eucalyptus samples were pretreated using 1-ethyl-3-methylimidazolium acetate (EmimOAc) at 110°C for 3h at biomass loadings of 5, 10, 15, 20 and 25wt%. All of the samples were chemically characterized and tested for enzymatic hydrolysis. Physical structures including biomass crystallinity and porosity were measured by X-ray diffraction (XRD) and small angle neutron scattering (SANS), respectively. SANS detected pores of radii ranging from ∼25 to 625Å, enabling assessment of contributions of pores with different sizes to increased porosity after pretreatment. Contrasting dependences of sugar conversion on white poplar and eucalyptus as a function of biomass loading were observed and cellulose crystalline structure was found to play an important role. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Small angle neutron scattering analyses and high temperature mechanical properties of nano-structured oxide dispersion strengthened steels produced via cryomilling

    SciTech Connect

    Kim, Jeoung Han; Byun, Thak Sang; Shin, Eunjoo; Seol, Jae-Bok; Young, Sung; Reddy, N. S.

    2015-08-17

    Three oxide dispersion-strengthened (ODS) steels are produced in order to investigate the effect of the mechanical alloying (MA) temperature on the microstructural evolution and high temperature mechanical properties. The microstructural evolution with different MA conditions is examined using small angle neutron scattering. As the MA temperature decreases, the density of the nanoclusters below 10 nm increases and their mean diameter decreases. A low temperature during MA leads to a high strength in the compression tests performed at 500 *C; however, this effect disappears in testing at 900 *C. The milling process at *70 *C exhibits excellent high fracture toughness, which is better than the benchmark material 14YWT-SM10. However, the *150 *C milling process results in significantly worse fracture toughness properties. The reasons for this strong temperature dependency are discussed.

  3. Bilayer thickness and lipid interface area in unilamellar extruded 1,2-diacylphosphatidylcholine liposomes: a small-angle neutron scattering study.

    PubMed

    Balgavý, P; Dubnicková, M; Kucerka, N; Kiselev, M A; Yaradaikin, S P; Uhríková, D

    2001-05-02

    Small-angle neutron scattering (SANS) experiments have been performed on large unilamellar liposomes prepared from 1,2-dilauroylphosphatidylcholine (DLPC), 1,2-dimyristoyl-phosphatidylcholine (DMPC) and 1,2-distearoylphosphatidylcholine (DSPC) in heavy water by extrusion through polycarbonate filters with 500 A pores. The neutron scattering intensity I(Q) in the region of scattering vectors Q corresponding to 0.0015 A(-2) < or = Q(2) < or = 0.0115 A(-2) was fitted using a step function model of bilayer neutron scattering length density and supposing that the liposomes are spherical and have a Gaussian distribution of radii. Using the lipid volumetric data, and supposing that the thickness of bilayer polar region equals to d(H) = 9+/-1 A and the water molecular volume intercalated in the bilayer polar region is the same as in the aqueous bulk aqueous phase, the steric bilayer thickness d(L), the lipid surface area A(L) and the number of water molecules per lipid molecule N intercalated in the bilayer polar region were obtained: d(L) = 41.58+/-1.93 A, A(L) = 57.18+/-1.00 A(2) and N = 6.53+/-1.93 in DLPC at 20 degrees C, d(L) = 44.26+/-1.42 A, A(L) = 60.01+/-0.75 A(2) and N = 7.37+/-1.94 in DMPC at 36 degrees C, and d(L) = 49.77+/-1.52 A, A(L) = 64.78+/-0.46 A(2) and N = 8.67+/-1.97 in DSPC at 60 degrees C. After correcting for area thermal expansivity alpha approximately 0.00417 K(-1), the lipid surface area shows a decrease with the lipid acyl chain length at 60 degrees C: A(L) = 67.56+/-1.18 A(2) in DLPC, A(L) = 66.33+/-0.83 A(2) in DMPC and A(L) = 64.78+/-0.46 A(2) in DSPC. It is also shown that a joint evaluation of SANS and small-angle X-ray scattering on unilamellar liposomes can be used to obtain the value of d(H) and the distance of the lipid phosphate group from the bilayer hydrocarbon region d(H1).

  4. Neutron guide system for small-angle neutron scattering instruments of the Jülich Centre for Neutron Science at the FRM-II

    NASA Astrophysics Data System (ADS)

    Radulescu, A.; Ioffe, A.

    2008-02-01

    Following the shut-down of the FRJ-2 research reactor in Jülich a large part of the neutron scattering instrumentation operating there is currently being moved to the FRM-II research reactor in Garching-München. The installation of these instruments requires the design and set-up of new neutron guides with geometrical and optical features imposed by the positioning of the instruments in the neutron guide hall and by the foreseen significant improvement of the instrument performance. Particularly three SANS diffractometers require a special approach due to on one hand, their pre-determined size and on the other hand, the demanded neutron wavelength range. Expected characteristics of three neutron guides (currently under construction) optimized using VITESS and McStas simulation packages, namely the vertically "S-shaped" guides serving the KWS2 and KWS1 conventional SANS instruments and the horizontally "S-shaped" guide serving the focusing KWS3 instrument, will be reported on.

  5. Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

    DOE PAGES

    Motokawa, Ryuhei; Kobayashi, Tohru; Endo, Hitoshi; ...

    2015-10-26

    This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl-substituted dibenzo-20-crown-6-ether (ace-DB20C6) with cesium ions (Cs+). SANS profiles obtained for the complex of ace-DB20C6 and Cs+ (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs+ coordination resulted in a more compact structure than the free ace-DB20C6. The data were fitted well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on density functional theory calculation was used. Furthermore, we conclude that the SANS analysis experimentallymore » supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs+ is formed with an ace-DB20C6/Cs molar ratio of 1/1 and (2) the two benzene rings of ace-DB20C6 fold around Cs+ above the center of the crown ether ring of ace-DB20C6.« less

  6. Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

    SciTech Connect

    Motokawa, Ryuhei; Kobayashi, Tohru; Endo, Hitoshi; Ikeda, Takashi; Yaita, Tsuyoshi; Suzuki, Shinichi; Narita, Hirokazu; Akutsu, Kazuhiro; Heller, William T.

    2015-10-26

    This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl-substituted dibenzo-20-crown-6-ether (ace-DB20C6) with cesium ions (Cs+). SANS profiles obtained for the complex of ace-DB20C6 and Cs+ (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs+ coordination resulted in a more compact structure than the free ace-DB20C6. The data were fitted well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on density functional theory calculation was used. Furthermore, we conclude that the SANS analysis experimentally supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs+ is formed with an ace-DB20C6/Cs molar ratio of 1/1 and (2) the two benzene rings of ace-DB20C6 fold around Cs+ above the center of the crown ether ring of ace-DB20C6.

  7. Small-angle neutron scattering investigation of as-irradiated, annealed and reirradiated reactor pressure vessel weld material of decommissioned reactor

    NASA Astrophysics Data System (ADS)

    Ulbricht, A.; Altstadt, E.; Bergner, F.; Viehrig, H.-W.; Keiderling, U.

    2011-09-01

    Small-angle neutron scattering (SANS) was applied to characterize the microstructure of weld material taken from the reactor pressure vessel (RPV) of the decommissioned VVER440 (230)-type nuclear power plant (NPP) Greifswald, Units 1, 2 and 4. The welding seam of highest neutron exposure of Unit 1 was subject to a large-scale annealing treatment in 1988 after about 11.5 effective years of operation. The same type of annealing was applied to Unit 2 in 1990 after about 11 effective years of operation. After final decommissioning of NPP Greifswald in 1990, RPV material was left in the reirradiated condition (Unit 1), in the as-annealed condition (Unit 2) and in the as-irradiated condition (Unit 4). Trepans of material from the highly irradiated RPV welds of these Units have recently become available for examination. The results of the SANS investigation are reported and compared with published results obtained for as-irradiated, post-irradiation annealed and reirradiated surveillance material of the same type. A general agreement was found indicating in particular the formation of irradiation-induced Cu-enriched clusters and efficient recovery as a result of the large-scale annealing treatments. The only essential difference was observed for the ratio of magnetic and nuclear scattering indicating differences of the cluster composition for the RPV wall and surveillance material.

  8. Measurement of porosity in a composite high explosive as a function of pressing conditions by ultra-small-angle neutron scattering with contrast variation

    SciTech Connect

    Mang, Joseph Thomas; Hjelm, Rex P; Francois, Elizabeth G

    2009-01-01

    We have used ultra-small-angle neutron scattering (USANS) with contrast variation to measure the porosity (voids and binder-filled regions) in a composite high explosive, PBX 9501, formulated with a deuterated binder. Little is known about the microstructure of pressed PBX 9501 parts and thus how it is affected by processing. Here, we explore the effect of varying the pressing intensity on the PBX 9501 microstructure. Disk-shaped samples of PBX 9501 were die-pressed with applied pressures ranging between 10,000 and 29,000 psi at 90 C. Five samples were prepared at each pressure that differed in the fraction of deuterated binder, facilitating variation of the neutron scattering length density contrast ({Delta}{rho}) and thus, the resolution of microstructural details. The sample composition was determined by calculation of the Porod Invariant as a function of {Delta}{rho} and compared with compositional estimates obtained from the bulk sample density. Structural modeling of the USANS data, at different levels of contrast, assuming both spherical and cylindrical morphologies, allowed the mean size and size distribution of voids and binder-filled regions to be determined. A decrease in the mean diameter of binder-filled regions was found with increasing pressing intensity, while the mean void diameter showed no significant change.

  9. Small-angle neutron scattering study of the short-range organization of dispersed CsNi[Cr(CN){sub 6}] nanoparticles

    SciTech Connect

    Ridier, Karl; Gillon, Béatrice; André, Gilles; Chaboussant, Grégory; Catala, Laure; Mazérat, Sandra; Mallah, Talal

    2015-09-21

    Prussian blue analogues magnetic nanoparticles (of radius R{sub 0} = 2.4–8.6 nm) embedded in PVP (polyvinylpyrrolidone) or CTA{sup +} (cetyltrimethylammonium) matrices have been studied using neutron diffraction and small angle neutron scattering (SANS) at several concentrations. For the most diluted particles in neutral PVP, the SANS signal is fully accounted for by a “single-particle” spherical form factor with no structural correlations between the nanoparticles and with radii comparable to those inferred from neutron diffraction. For higher concentration in PVP, structural correlations modify the SANS signal with the appearance of a structure factor peak, which is described using an effective “mean-field” model. A new length scale R{sup * }≈ 3R{sub 0}, corresponding to an effective repulsive interaction radius, is evidenced in PVP samples. In CTA{sup +}, electrostatic interactions play a crucial role and lead to a dense layer of CTA{sup +} around the nanoparticles, which considerably alter the SANS patterns as compared to PVP. The SANS data of nanoparticles in CTA{sup +} are best described by a core-shell model without visible inter-particle structure factor.

  10. SASBDB, a repository for biological small-angle scattering data

    PubMed Central

    Valentini, Erica; Kikhney, Alexey G.; Previtali, Gianpietro; Jeffries, Cy M.; Svergun, Dmitri I.

    2015-01-01

    Small-angle X-ray and neutron scattering (SAXS and SANS) are fundamental tools used to study the global shapes of proteins, nucleic acids, macromolecular complexes and assemblies in solution. Due to recent advances in instrumentation and computational methods, the quantity of experimental scattering data and subsequent publications is increasing dramatically. The need for a global repository allowing investigators to locate and access experimental scattering data and associated models was recently emphasized by the wwPDB small-angle scattering task force (SAStf). The small-angle scattering biological data bank (SASBDB) www.sasbdb.org has been designed in accordance with the plans of the SAStf as part of a future federated system of databases for biological SAXS and SANS. SASBDB is a comprehensive repository of freely accessible and fully searchable SAS experimental data and models that are deposited together with the relevant experimental conditions, sample details and instrument characteristics. At present the quality of deposited experimental data and the accuracy of models are manually curated, with future plans to integrate automated systems as the database expands. PMID:25352555

  11. Structural hierarchy of chromatin in chicken erythrocyte nuclei based on small-angle neutron scattering: Fractal nature of the large-scale chromatin organization

    SciTech Connect

    Lebedev, D. V. Filatov, M. V.; Kuklin, A. I.; Islamov, A. Kh.; Stellbrink, J.; Pantina, R. A.; Denisov, Yu. Yu.; Toperverg, B. P.; Isaev-Ivanov, V. V.

    2008-01-15

    The chromatin organization in chicken erythrocyte nuclei was studied by small-angle neutron scattering in the scattering-vector range from 1.5 x 10{sup -1} to 10{sup -4} A{sup -1} with the use of the contrast-variation technique. This scattering-vector range corresponds to linear dimensions from 4 nm to 6 {mu}m and covers the whole hierarchy of chromatin structures, from the nucleosomal structure to the entire nucleus. The results of the present study allowed the following conclusions to be drawn: (1) both the chromatin-protein structure and the structure of the nucleic acid component in chicken erythrocyte nuclei have mass-fractal properties, (2) the structure of the protein component of chromatin exhibits a fractal behavior on scales extending over two orders of magnitude, from the nucleosomal size to the size of an entire nucleus, and (3) the structure of the nucleic acid component of chromatin in chicken erythrocyte nuclei is likewise of a fractal nature and has two levels of organization or two phases with the crossover point at about 300-400 nm.

  12. Small-Angle Neutron Scattering and Electron Microscopy Study of the Wet and Dry High-Temperature Oxidation of Alumina- and Chromia- Forming Stainless Steels

    SciTech Connect

    Rother, Gernot; Keiser, James R; Brady, Michael P; Unocic, Kinga A; Anovitz, Lawrence {Larry} M; Littrell, Ken; Meisner, Roberta Ann; Santella, Michael L; Wesolowski, David J; Cole, David R

    2012-01-01

    Foils of T347 stainless steel and a developmental alumina-forming austenitic (AFA) stainless steel were oxidized at 800 C in dry air, air with 10% H2O, and air with 10% D2O. The T347 foils exhibited a transition to rapid Fe-base oxide formation between 24 and 72 h of exposure in H2O and D2O, but exhibited protective Cr-rich oxide formation in dry air. In contrast, only thin, protective Al-rich oxide surfaces were observed for the AFA alloy foils under all conditions studied. Changes in the small angle neutron scattering (SANS) signal were observed for the T347 stainless steel as a function of oxidation time in dry air, attributed to oxide grain growth and porosity formation/partial scale detachment associated with spinel phase at the scale/gas interface. For the AFA alloy, only minor changes in scattering as a result of oxidation time were observed. For both T347 and AFA, similar scattering was observed in dry and wet air (H2O and D2O) exposure. This finding indicates that water vapor exposure did not induce significant morphological changes in the oxide scales (such as increased porosity) in the 5-300 nm size regime accessed by SANS.

  13. Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering. I. Application to industrial multi-component nanocomposites.

    PubMed

    Noda, Yohei; Koizumi, Satoshi; Masui, Tomomi; Mashita, Ryo; Kishimoto, Hiroyuki; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shin-Ichi; Ohishi, Kazuki; Suzuki, Jun-Ichi

    2016-12-01

    Dynamic nuclear polarization (DNP) at low temperature (1.2 K) and high magnetic field (3.3 T) was applied to a contrast variation study in small-angle neutron scattering (SANS) focusing on industrial rubber materials. By varying the scattering contrast by DNP, time-of-flight SANS profiles were obtained at the pulsed neutron source of the Japan Proton Accelerator Research Complex (J-PARC). The concentration of a small organic molecule, (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO), was carefully controlled by a doping method using vapour sorption into the rubber specimens. With the assistance of microwave irradiation (94 GHz), almost full polarization of the paramagnetic electronic spin of TEMPO was transferred to the spin state of hydrogen (protons) in the rubber materials to obtain a high proton spin polarization (PH). The following samples were prepared: (i) a binary mixture of styrene-butadiene random copolymer (SBR) with silica particles (SBR/SP); and (ii) a ternary mixture of SBR with silica and carbon black particles (SBR/SP/CP). For the binary mixture (SBR/SP), the intensity of SANS significantly increased or decreased while keeping its q dependence for PH = -35% or PH = 40%, respectively. The q behaviour of SANS for the SBR/SP mixture can be reproduced using the form factor of a spherical particle. The intensity at low q (∼0.01 Å(-1)) varied as a quadratic function of PH and indicated a minimum value at PH = 30%, which can be explained by the scattering contrast between SP and SBR. The scattering intensity at high q (∼0.3 Å(-1)) decreased with increasing PH, which is attributed to the incoherent scattering from hydrogen. For the ternary mixture (SBR/SP/CP), the q behaviour of SANS was varied by changing PH. At PH = -35%, the scattering maxima originating from the form factor of SP prevailed, whereas at PH = 29% and PH = 38%, the scattering maxima disappeared. After decomposition of the total SANS according to inverse matrix calculations

  14. Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering. I. Application to industrial multi-component nanocomposites1

    PubMed Central

    Noda, Yohei; Koizumi, Satoshi; Masui, Tomomi; Mashita, Ryo; Kishimoto, Hiroyuki; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shin-ichi; Ohishi, Kazuki; Suzuki, Jun-ichi

    2016-01-01

    Dynamic nuclear polarization (DNP) at low temperature (1.2 K) and high magnetic field (3.3 T) was applied to a contrast variation study in small-angle neutron scattering (SANS) focusing on industrial rubber materials. By varying the scattering contrast by DNP, time-of-flight SANS profiles were obtained at the pulsed neutron source of the Japan Proton Accelerator Research Complex (J-PARC). The concentration of a small organic molecule, (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO), was carefully controlled by a doping method using vapour sorption into the rubber specimens. With the assistance of microwave irradiation (94 GHz), almost full polarization of the paramagnetic electronic spin of TEMPO was transferred to the spin state of hydrogen (protons) in the rubber materials to obtain a high proton spin polarization (P H). The following samples were prepared: (i) a binary mixture of styrene–butadiene random copolymer (SBR) with silica particles (SBR/SP); and (ii) a ternary mixture of SBR with silica and carbon black particles (SBR/SP/CP). For the binary mixture (SBR/SP), the intensity of SANS significantly increased or decreased while keeping its q dependence for P H = −35% or P H = 40%, respectively. The q behaviour of SANS for the SBR/SP mixture can be reproduced using the form factor of a spherical particle. The intensity at low q (∼0.01 Å−1) varied as a quadratic function of P H and indicated a minimum value at P H = 30%, which can be explained by the scattering contrast between SP and SBR. The scattering intensity at high q (∼0.3 Å−1) decreased with increasing P H, which is attributed to the incoherent scattering from hydrogen. For the ternary mixture (SBR/SP/CP), the q behaviour of SANS was varied by changing P H. At P H = −35%, the scattering maxima originating from the form factor of SP prevailed, whereas at P H = 29% and P H = 38%, the scattering maxima disappeared. After decomposition of the total SANS according to inverse matrix

  15. The determination of the void structure of microporous coals by small-angle neutron scattering: Void geometry and structure in Illinois No. 6 bituminous coal

    NASA Astrophysics Data System (ADS)

    Gethner, Jon S.

    1986-02-01

    The access of solvents and reactants to the microvoid volume in porous materials such as coal plays an important role in determining the overall chemistry which takes place during a variety of chemical transformations including oxidation, combustion, and pyrolysis. The structure and surface composition of these voids were studied using small-angle neutron scattering techniques to examine selectively the subset of the overall void volume distribution which comprises the microvoid volume. Powdered Illinois No. 6 coal containing approximately 20% void volume was slurried in several different aqueous and cyclohexane solutions. The solutions used had various hydrogen-to-deuterium ratios in order to contrast match most of the open pore volume thereby making the microvoid volume visible. The microvoid volume observed is characterized as elongated voids having a fairly well-defined diameter and surface composition. The scattering intensity from the microvoid volume shows a well-defined Porod region, indicating that the smallest void dimension is resolved by the instrumental configuration employed. A Guinier region exhibiting Q-1 behavior, which is characteristic of elongated structures, is also observed. The average radius of a circular cross section of these voids is found to be 25.4 Å. The microvoids are found to be completely filled by aqueous solutions so that the residual neutron scattering, which is not eliminated by the contrast-matching aqueous solution, is due to the organic matrix structure. Nonaqueous mixtures of cyclohexane cannot fill the entire microvoid volume as effectively as the aqueous mixtures. The scattering differences observed between the aqueous and nonaqueous filled coal indicates that the surface of the microvoids is predominantly aliphatic in character with the principal compositional variation being the presence or absence of acidic functionality on the surface.

  16. Distribution of functional groups in periodic mesoporous organosilica materials studied by small-angle neutron scattering with in situ adsorption of nitrogen.

    PubMed

    Sharifi, Monir; Wallacher, Dirk; Wark, Michael

    2012-01-01

    Periodic mesoporous materials of the type (R'O)(3)Si-R-Si(OR')(3) with benzene as an organic bridge and a crystal-like periodicity within the pore walls were functionalized with SO(3)H or SO(3) (-) groups and investigated by small-angle neutron scattering (SANS) with in situ nitrogen adsorption at 77 K. If N(2) is adsorbed in the pores the SANS measurements show a complete matching of all of the diffraction signals that are caused by the long-range ordering of the mesopores in the benzene-PMO, due to the fact that the benzene-PMO walls possess a neutron scattering length density (SLD) similar to that of nitrogen in the condensed state. However, signals at higher q-values (>1 1/Å) are not affected with respect to their SANS intensity, even after complete pore filling, confirming the assumption of a crystal-like periodicity within the PMO material walls due to π-π interactions between the organic bridges. The SLD of pristine benzene-PMO was altered by functionalizing the surface with different amounts of SO(3)H-groups, using the grafting method. For a low degree of functionalization (0.81 mmol SO(3)H·g(-1)) and/or an inhomogeneous distribution of the SO(3)H-groups, the SLD changes only negligibly, and thus, complete contrast matching is still found. However, for higher amounts of SO(3)H-groups (1.65 mmol SO(3)H·g(-1)) being present in the mesopores, complete matching of the neutron diffraction signals is no longer observed proving that homogeneously distributed SO(3)H-groups on the inner pore walls of the benzene-PMO alter the SLD in a way that it no longer fits to the SLD of the condensed N(2).

  17. Model-based Approaches for the Determination of Lipid Bilayer Structure from Small-Angle Neutron and X-ray Scattering Data

    SciTech Connect

    Heberle, Frederick A; Pan, Jianjun; Standaert, Robert F; Drazba, Paul; Kucerka, Norbert; Katsaras, John

    2012-01-01

    Some of our recent work has resulted in the detailed structures of fully hydrated, fluid phase phosphatidylcholine (PC) and phosphatidylglycerol (PG) bilayers. These structures were obtained from the joint refinement of small-angle neutron and X-ray data using the scattering density profile (SDP) models developed by Ku erka et al. (Ku erka et al. 2012; Ku erka et al. 2008). In this review, we first discuss models for the standalone analysis of neutron or X-ray scattering data from bilayers, and assess the strengths and weaknesses inherent in these models. In particular, it is recognized that standalone data do not contain enough information to fully resolve the structure of inherently disordered fluid bilayers, and therefore may not provide a robust determination of bilayer structural parameters, including the much sought after area per lipid. We then discuss the development of matter density-based models (including the SDP model) that allow for the joint refinement of different contrast neutron and X-ray data sets, as well as the implementation of local volume conservation in the unit cell (i.e., ideal packing). Such models provide natural definitions of bilayer thicknesses (most importantly the hydrophobic and Luzzati thicknesses) in terms of Gibbs dividing surfaces, and thus allow for the robust determination of lipid areas through equivalent slab relationships between bilayer thickness and lipid volume. In the final section of this review, we discuss some of the significant findings/features pertaining to structures of PC and PG bilayers as determined from SDP model analyses.

  18. Interaction of the Full-length Bax Protein with Biomimetic Mitochondrial Liposomes: A Small-Angle Neutron Scattering and Fluorescence Study

    SciTech Connect

    Satsoura, D; Kucerka, Norbert; Shivakumar, S; Pencer, J; Griffiths, C; Leber, B; Andrews, D.W; Katsaras, John; Fradin, C

    2012-01-01

    In response to apoptotic stimuli, the pro-apoptotic protein Bax inserts in the outer mitochondrial membrane, resulting in the formation of pores and the release of several mitochondrial components, and sealing the cell's fate. To study the binding of Bax to membranes, we used an in vitro system consisting of 50 nm diameter liposomes prepared with a lipid composition mimicking that of mitochondrial membranes in which recombinant purified full-length Bax was inserted via activation with purified tBid. We detected the association of the protein with the membrane using fluorescence fluctuation methods, and found that it could well be described by an equilibrium between soluble and membrane-bound Bax and that at a high protein-toliposome ratio the binding seemed to saturate at about 15 Bax proteins per 50 nm diameter liposome. We then obtained structural data for samples in this saturated binding regime using small-angle neutron scattering under different contrast matching conditions. Utilizing a simple model to fit the neutron data, we observed that a significant amount of the protein mass protrudes above the membrane, in contrast to the conjecture that all of the membrane-associated Bax states are umbrella-like. Upon protein binding, we also observed a thinning of the lipid bilayer accompanied by an increase in liposome radius, an effect reminiscent of the action of antimicrobial peptides on membranes.

  19. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of the Effect of Mn on the Nanostructural Features formed in Irradiated Fe-Cu-Mn Alloys

    SciTech Connect

    Glade, S C; Wirth, B D; Asoka-Kumar, P; Odette, G R; Sterne, P A; Howell, R H

    2003-02-27

    The size, number density and composition of the nanometer defects responsible for the hardening and embrittlement in irradiated Fe-0.9wt.% Cu and Fe-0.9wt.% Cu-1.0wt% Mn model reactor pressure vessel alloys were measured using small angle neutron scattering and positron annihilation spectroscopy. These alloys were irradiated at 290 C to relatively low neutron fluences (E > 1 MeV, 6.0 x 10{sup 20} to 4.0 x 10{sup 21} n/m{sup 2}) in order to study the effect of manganese on the nucleation and growth of copper rich precipitates and secondary defect features. Copper rich precipitates were present in both alloys following irradiation. The Fe-Cu-Mn alloy had smaller precipitates and a larger number density of precipitates, suggesting Mn segregation at the iron matrix-precipitate interface which reduces the interfacial energy and in turn the driving force for coarsening. Mn also retards the precipitation kinetics and inhibits large vacancy cluster formation, suggesting a strong Mn-vacancy interaction which reduces radiation enhanced diffusion.

  20. Ferromagnetic correlations in Yb2Ti2O7 as revealed by small angle neutron scattering techniques

    NASA Astrophysics Data System (ADS)

    Buhariwalla, Connor; Ma, Qianli; Debeer-Schmitt, Lisa; Dabkowska, Hanna; Gaulin, Bruce

    We report low temperature SANS measurements on frustrated Seff=1/2 XY pyrochlore magnet Yb2Ti2O7. The ground state of this material has been proposed as a realization of a quantum spin ice; however, the low temperature phase behaviour has been complicated by sample dependencies believed to be related to weak ``stuffing''. Our SANS study focuses on the low Q structure of elastic ``rods'' of magnetic scattering which extend from Q=0 along the 111 direction. Using a single crystal sample, we characterize the low Q (<0.2Å-1) temperature dependence of this structured diffuse scattering intensity to T=30mK, passing through the enigmatic heat capacity anomaly near Tc=200mK. The temperature dependence of this diffuse scattering near Q=0 is largely consistent with that measured previously near 111.

  1. Alteration of water structure by peptide clusters revealed by neutron scattering in the small-angle region (below 1 Å–1)

    SciTech Connect

    Daidone, Isabella; Iacobucci, Claudio; McLain, Sylvia; Smith, Jeremy C.

    2012-10-03

    Solution scattering of neutrons and x-rays can provide direct information on local interactions of importance for biomolecular folding and structure. Here, neutron scattering experiments are combined with molecular-dynamics simulation to interpret the scattering signal of a series of dipeptides with varying degrees of hydrophobicity (GlyAla, GlyPro, and AlaPro) in concentrated aqueous solution (1:20 solute/water ratio) in which the peptides form large segregates (up to 50 60 amino acids). Two main results are found: 1), the shift to lower Q of the so-called water-ring peak (Q ≈ 2Å–1) arises mainly from an overlap of water-peptide and peptide-peptide correlations in the region of 1.3 < Q < 2Å–1 , rather than from a shift of the water signal induced by the presence of the clusters; and 2), in the low-Q region (Q ≈ 0.6Å–1) a positive peak is observed originating from both the solute-solute correlations and changes in the water structure induced by the formation of the clusters. In particular, the water molecules are found to be more connected than in the bulk with hydrogen-bonding directions tangential to the exposed hydrophobic surfaces, and this effect increases with increasing peptide hydrophobicity. Lastly, this work demonstrates that important information on the (hydrophobic) hydration of biomolecules can be obtained in the very-small-angle region.

  2. Report detailing comparative analysis of results from high flux isotope reactor and national institute of standards technology small-angle neutron scattering experiments

    SciTech Connect

    Sokolov, Mikhail A.; Littrell, Ken; Wells, Peter; Cunningham, Nicholas J.

    2015-09-01

    discussed above, see Ref. [5] and [6] for details. UCSB has performed a large number of SANS experiments in the past at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). These data are taken from RPV steels irradiated in a wide range of flux-fluence space and will be very useful in comparing to the upcoming UCSB ATR-2 irradiation characterization since most of the SANS experiments with ATR-2 materials will be performed at ORNL High Flux Isotope Reactor (HFIR). However in the previous report [7], some discrepancies were observed between HFIR and NCNR generated data. One of the hypotheses was that there was some kind of extra scattering occurring off the sample holders that results in the HFIR curves falling above the NCNR curves. To test this hypothesis, UCSB provided thermally aged samples that have been previously run at NCNR to ORNL for testing at HFIR while ORNL performed some improvements to experimental set up at HFIR. This report provides the status for the Level 3 Milestone (M3LW-15OR0402013), Complete report detailing comparative analysis of results from High Flux Isotope Reactor and National Institute of Standards and Technology small-angle neutron scattering experiments. This milestone is associated with small-angle neutron scattering characterization at the High Flux Isotope Reactor of various model alloys that had been previously characterized at NCNR by UCSB.

  3. Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

    DOE PAGES

    Han, Youngkyu; Ahn, Suk-kyun; Zhang, Zhe; ...

    2016-06-01

    We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotubemore » particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. In conclusion, this method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.« less

  4. Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

    SciTech Connect

    Han, Youngkyu; Ahn, Suk-kyun; Zhang, Zhe; Smith, Gregory S.; Do, Changwoo

    2016-06-01

    We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. In conclusion, this method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

  5. Analysis of the solution structure of Thermosynechococcus elongatus photosystem I in n-dodecyl-β-d-maltoside using small-angle neutron scattering and molecular dynamics simulation

    SciTech Connect

    Le, Rosemary K.; Harris, Bradley J.; Iwuchukwu, Ifeyinwa J.; Bruce, Barry D.; Cheng, Xiaolin; Qian, Shuo; Heller, William T.; O’Neill, Hugh; Frymier, Paul D.

    2014-05-01

    Small-angle neutron scattering (SANS) and molecular dynamics (MD) simulation were used to investigate the structure of trimeric photosystem I (PSI) from Thermosynechococcus elongatus (T. elongatus) stabilized in n-dodecyl-β-d-maltoside (DDM) detergent solution. Scattering curves of detergent and protein–detergent complexes were measured at 18% D2O, the contrast match point for the detergent, and 100% D2O, allowing observation of the structures of protein/detergent complexes. It was determined that the maximum dimension of the PSI–DDM complex was consistent with the presence of a monolayer belt of detergent around the periphery of PSI. A dummy-atom reconstruction of the shape of the complex from the SANS data indicates that the detergent envelope has an irregular shape around the hydrophobic periphery of the PSI trimer rather than a uniform, toroidal belt around the complex. A 50 ns MD simulation model (a DDM ring surrounding the PSI complex with extra interstitial DDM) of the PSI–DDM complex was developed for comparison with the SANS data. The results suggest that DDM undergoes additional structuring around the membrane-spanning surface of the complex instead of a simple, relatively uniform belt, as is generally assumed for studies that use detergents to solubilize membrane proteins.

  6. Matchout deuterium labelling of proteins for small-angle neutron scattering studies using prokaryotic and eukaryotic expression systems and high cell-density cultures.

    PubMed

    Dunne, O; Weidenhaupt, M; Callow, P; Martel, A; Moulin, M; Perkins, S J; Haertlein, M; Forsyth, V T

    2017-07-01

    Small-angle neutron scattering (SANS) is a powerful technique for the characterisation of macromolecular structures and interactions. Its main advantage over other solution state approaches is the ability to use D2O/H2O solvent contrast variation to selectively match out specific parts of a multi-component system. While proteins, nucleic acids, and lipids are readily distinguished in this way, it is not possible to locate different parts of a protein-protein system without the introduction of additional contrast by selective deuteration. Here, we describe new methods by which 'matchout labelled' proteins can be produced using Escherichia coli and Pichia pastoris expression systems in high cell-density cultures. The method is designed to produce protein that has a scattering length density that is very close to that of 100% D2O, providing clear contrast when used with hydrogenated partner proteins in a complex. This allows the production of a single sample system for which SANS measurements at different solvent contrasts can be used to distinguish and model the hydrogenated component, the deuterated component, and the whole complex. The approach, which has significant cost advantages, has been extensively tested for both types of expression system.

  7. Investigation of the pore structure and morphology of cellulose acetate membranes using small-angle neutron scattering. 2: Ultrafiltration and reverse-osmosis membranes

    SciTech Connect

    Kulkarni, S.; Krause, S. ); Wignall, G.D. . Solid State Div.)

    1994-11-07

    Pore structure in cellulose acetate ultrafiltration (UF) and reverse-osmosis (RO) membranes has been studied using small-angle neutron scattering. Scattering experiments were carried out on dry membranes as well as on membranes swollen with deuterated solvents (D[sub 2]O and CD[sub 3]OD). In addition, the RO membranes were studied both before and after annealing (a process of heating a membrane in a water bath at [approximately]75 C to improve its separation properties). The pore surface in UF membranes was found to be smooth and nonfractal, as evidenced by the fourth power law behavior at high Q. Values of average pore sizes obtained for dry and solvent swollen membranes agree well with pore sizes obtained by other methods. For cellulose acetate RO membranes in their dry state, the unannealed membrane appears to consist of two discrete pore size distributions in the intermediate and high Q region while the annealed membrane contains a much wider distribution of pore sizes. These results give a good account of the changes occurring in the structure of RO membranes as a result of annealing, and agree well with the prediction of other authors.

  8. Investigation of the pore structure and morphology of cellulose acetate membranes using small-angle neutron scattering. 1: Cellulose acetate active layer membranes

    SciTech Connect

    Kulkarni, S.; Krause, S. ); Wignall, G.D. . Solid State Div.); Hammouda, B. . Center for High Resolution Neutron Scattering)

    1994-11-07

    The structure of ultrathin cellulose acetate membranes, known as active layer membranes, has been investigated using small-angle neutron scattering. These membranes are known to have structural and functional similarity to the surface or skin layer in commercial reverse-osmosis (RO) membranes and hence are useful model systems for understanding the structure of the RO membrane skin layer. Active layer membranes were studied after swelling them with either D[sub 2]O or CD[sub 3]OD. The results in both cases clearly indicated the presence of very small (10--20 [angstrom]) porous structures in the membrane. The presence of such pores has been a subject of long-standing controversy in this area. The data were analyzed using a modified Debye-Bueche analysis and the resultant membrane structure was seen to agree well with structural information from electron microscopic studies. Finally, a possible explanation for the differences in scattering observed between the D[sub 2]O swollen membranes and the CD[sub 3]OD swollen membranes has been presented.

  9. Small-angle neutron scattering study of protein crowding in liquid and solid phases: lysozyme in aqueous solution, frozen solution, and carbohydrate powders.

    PubMed

    Curtis, Joseph E; Nanda, Hirsh; Khodadadi, Sheila; Cicerone, Marcus; Lee, Hyo Jin; McAuley, Arnold; Krueger, Susan

    2012-08-16

    The structure, interactions, and interprotein configurations of the protein lysozyme were studied in a variety of phases. These properties have been studied under a variety of solution conditions before, during, and after freezing and after freeze-drying in the presence of glucose and trehalose. Contrast variation experiments have also been performed to determine which features of the scattering in the frozen solutions are from the protein and which are from the ice structure. Data from lysozyme at concentrations ranging from 1 to 100 mg/mL in solution and water ice with NaCl concentrations ranging from 0 to 0.4 mol/L are fit to model small-angle neutron scattering (SANS) intensity functions consisting of an ellipsoidal form factor and either a screened-Coulomb or hard-sphere structure factor. Parameters such as protein volume fraction and long dimension are followed as a function of temperature and salt concentration. The SANS results are compared to real space models of concentrated lysozyme solutions at the same volume fractions obtained from Monte Carlo simulations. A cartoon representation of the frozen lysozyme solution in 0 mol/L NaCl is presented based on the SANS and Monte Carlo results, along with those obtained from other complementary methods.

  10. Onset and Nature of Fracture of Uniaxially Compressed Gun Propellants. A Small Angle Neutron and X-ray Scattering Study

    DTIC Science & Technology

    1993-08-01

    Avogadro constant , Di is the mass density of material i, the sums are over the k atom types in material i, nk is the number of atoms of type k, Wk is the...subsequent analysis. This includes the ability to obtain averages for constant scattering angle (0) as functions of the azimuthal angle (0). If radial...values for the B specimen are plotted against axial orientation with strain level for each curve remaining constant . The general trend indicated is an

  11. Droplet polydispersity and shape fluctuations in AOT [bis(2-ethylhexyl)sulfosuccinate sodium salt] microemulsions studied by contrast variation small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Arleth, Lise; Pedersen, Jan Skov

    2001-06-01

    Microemulsions consisting of AOT water, and decane or iso-octane are studied in the region of the phase diagram where surfactant covered water droplets are formed. The polydispersity and shape fluctuations of the microemulsion droplets are determined and compared in the two different alkane types. Conductivity measurements show that there is a pronounced dependence of the temperature behavior of the microemulsion on the type of alkane used. In both cases the microemulsion droplets start to form larger aggregates when the temperature increases. But in the system with decane this aggregation temperature occurs at a temperature about 10 °C lower than in a similar system with iso-octane. Aggregation phenomena are avoided and the two systems are at approximately the same reduced temperature with respect to the aggregation temperature when the temperature of the AOT/D2O/decane microemulsion is 10 °C and the temperature of the AOT/D2O/iso-octane microemulsion is 20 °C. Contrast variation small-angle neutron scattering measurements are performed at these temperatures on systems with volume fractions of 5% D2O+AOT by varying the scattering length density of the alkane. The small-angle scattering for 11 different contrasts evenly distributed around the match points are studied for each sample. The scattering data for the different contrasts are analyzed using a molecular constrained model for ellipsoidal droplets of water covered by AOT, interacting as polydisperse hard spheres. All contrasts are fitted simultaneously by taking the different contrast factors into account. The analysis show that at the same reduced temperature with respect to the aggregation temperature the droplet size, polydispersity index, the size of the shape fluctuations are similar in the two systems. A polydispersity index (σ/R of the Gaussian size distribution) of 16% and an average axis ratio of the droplets of 1.56 is found in the AOT/D2O/decane microemulsion. In the AOT/D2O/iso-octane system

  12. Tuning the instrument resolution using chopper and time of flight at the small-angle neutron scattering diffractometer KWS-2.

    PubMed

    Radulescu, Aurel; Székely, Noémi Kinga; Polachowski, Stephan; Leyendecker, Marko; Amann, Matthias; Buitenhuis, Johan; Drochner, Matthias; Engels, Ralf; Hanslik, Romuald; Kemmerling, Günter; Lindner, Peter; Papagiannopoulos, Aristeidis; Pipich, Vitaliy; Willner, Lutz; Frielinghaus, Henrich; Richter, Dieter

    2015-12-01

    Following demand from the user community regarding the possibility of improving the experimental resolution, the dedicated high-intensity/extended Q-range SANS diffractometer KWS-2 of the Jülich Centre for Neutron Science at the Heinz Maier-Leibnitz Center in Garching was equipped with a double-disc chopper with a variable opening slit window and time-of-flight (TOF) data acquisition option. The chopper used in concert with a dedicated high-intensity velocity selector enables the tuning at will of the wavelength resolution Δλ/λ within a broad range, from 20% (standard) down to 2%, in a convenient and safe manner following pre-planned or spontaneous decisions during the experiment. The new working mode is described in detail, and its efficiency is demonstrated on several standard samples with known properties and on a completely new crystallizable copolymer system, which were investigated using both the conventional (static) and TOF modes.

  13. Tuning the instrument resolution using chopper and time of flight at the small-angle neutron scattering diffractometer KWS-2

    PubMed Central

    Radulescu, Aurel; Székely, Noémi Kinga; Polachowski, Stephan; Leyendecker, Marko; Amann, Matthias; Buitenhuis, Johan; Drochner, Matthias; Engels, Ralf; Hanslik, Romuald; Kemmerling, Günter; Lindner, Peter; Papagiannopoulos, Aristeidis; Pipich, Vitaliy; Willner, Lutz; Frielinghaus, Henrich; Richter, Dieter

    2015-01-01

    Following demand from the user community regarding the possibility of improving the experimental resolution, the dedicated high-intensity/extended Q-range SANS diffractometer KWS-2 of the Jülich Centre for Neutron Science at the Heinz Maier-Leibnitz Center in Garching was equipped with a double-disc chopper with a variable opening slit window and time-of-flight (TOF) data acquisition option. The chopper used in concert with a dedicated high-intensity velocity selector enables the tuning at will of the wavelength resolution Δλ/λ within a broad range, from 20% (standard) down to 2%, in a convenient and safe manner following pre-planned or spontaneous decisions during the experiment. The new working mode is described in detail, and its efficiency is demonstrated on several standard samples with known properties and on a completely new crystallizable copolymer system, which were investigated using both the conventional (static) and TOF modes. PMID:26664343

  14. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    SciTech Connect

    Putra, Edy Giri Rachman; Patriati, Arum

    2015-04-16

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  15. Characterization of the Decaheme c-type Cytochrome OmcA in Solution and on Hematite Surfaces by Small Angle X-ray Scattering and Neutron Reflectometry

    SciTech Connect

    Johs, Alexander; Shi, Liang; Droubay, Timothy; Ankner, John Francis; Liang, Liyuan

    2010-01-01

    The outer membrane protein OmcA is an 85 kDa decaheme c-type cytochrome located on the surface of the dissimilatory metal reducing bacterium Shewanella oneidensis MR-1. It is assumed to mediate electron shuttling, generated by the bacteria s metabolism, to extracellular acceptors that include solid metal oxides such as hematite ( -Fe2O3). To investigate the mechanism by which OmcA interacts with hematite, we purified OmcA and characterized its solution structure by small angle X-ray scattering (SAXS) and its interaction with hematite by neutron reflectometry (NR). SAXS results showed that OmcA is a monomer that adopts a flat ellipsoidal shape with a dimension of 3.4 9.0 6.5 nm3. Changes in redox state affect OmcA conformation. In addition, OmcA interacts with small organic ligands known to act as electron shuttle molecules, such as flavin mononucleotide (FMN), resulting in the formation of high molecular weight assemblies. A model system, developed using NR to study the interaction of OmcA with hematite, shows that OmcA forms a well-defined monomolecular layer on hematite surfaces. This allows OmcA to preferentially interact with hematite in a conformation that maximizes its contact area with the mineral surface. Overall, these results provide experimental and quantitative evidence for OmcA reduction of solid metal oxides involving both direct and indirect mechanisms.

  16. Small-angle neutron scattering analysis of Mn–C clusters in high-manganese 18Mn–0.6C steel

    SciTech Connect

    Kang, Mihyun; Shin, Eunjoo; Woo, Wanchuck; Lee, Young-Kook

    2014-10-15

    Nanometer-scale particles (Mn–C clusters) were analyzed quantitatively using small-angle neutron scattering in 18Mn–0.6C (wt.%) austenite high-manganese steel. The size, number, and volume fraction of the particles were determined as a function of strain (0, 5, 15, 30, 45, 50%) at different temperatures (25 and 100 °C). The diameter of the cluster ranges from 2 to 14 nm in the matrix. The total volume fraction of the cluster significantly increases from 2.7 × 10{sup −6} to 8.7 × 10{sup −6} as the strain increases. Such clustering phenomenon is correlated to the serration behavior under loading in high-manganese steels. - Highlights: • Show Mn-C clustering as function of strain in 18Mn-0.6C TWIP steel. • Determine the size, number, and volume fraction of clusters quantitatively. • Compare the clustering behavior at 25 and 100 °C.

  17. Effect of successive alkylation of N,N-dialkyl amides on the complexation behavior of uranium and thorium: solvent extraction, small angle neutron scattering, and computational studies.

    PubMed

    Verma, Parveen Kumar; Pathak, Priyanath N; Kumari, Neelam; Sadhu, Biswajit; Sundararajan, Mahesh; Aswal, Vinod Kumar; Mohapatra, Prasanta Kumar

    2014-12-11

    The effect of successive alkylation of the Cα atom adjacent to the carbonyl group in N,N-dialkyl amides (i.e., di(2-ethylhexyl)acetamide (D2EHAA), di(2-ethylhexyl)propionamide (D2EHPRA), di(2-ethylhexyl)isobutyramide (D2EHIBA), and di(2-ethylhexyl)pivalamide (D2EHPVA)) on the extraction behavior of hexavalent uranium (U(VI)) and tetravalent thorium (Th(IV)) ions has been investigated. These studies show that the extraction of Th(IV) is significantly suppressed compared to that of U(VI) with increased branching at the Cα atom adjacent to the carbonyl group. Small angle neutron scattering (SANS) studies showed an increased aggregation tendency in the presence of nitric acid and metal ions. D2EHAA showed more aggregation compared to its branched homologues, which explains its capacity for higher extraction of metal ions. These experimental observations were further supported by density function theory calculations, which provided structural evidence of differential binding affinities of these extractants for uranyl cations. The complexation process is primarily controlled by steric and electronic effects. Quantum chemical calculations showed that local hardness and polarizability can be extremely useful inputs for designing novel extractants relevant to a nuclear fuel cycle.

  18. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering

    DOE PAGES

    Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; ...

    2015-01-08

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin, which links the CD44 assembled receptor signaling complexes to the cytoskeletal actin and organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered and adopts an autoinhibited conformation, which prevents CD44ct from binding directly to activated Ezrin in solution. Binding to the signaling lipid phosphatidylinositol 4,5-biphosphlate (PIP2) disrupts autoinhibition in CD44ct, and activates CD44ct to associate with Ezrin.more » Further, using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific hetero-tetramer complex of CD44ct with Ezrin. This study reveals a novel autoregulation mechanism in the cytoplasmic tail of CD44 and the role of PIP2 in mediating the assembly of multimeric CD44ct-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of multimeric PIP2-CD44-Ezrin complexes.« less

  19. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering

    SciTech Connect

    Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; Stanley, Christopher B.; Do, Changwoo; Heller, William T.; Aggarwal, Aneel K.; Callaway, David J.E.; Bu, Zimei

    2015-01-08

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin, which links the CD44 assembled receptor signaling complexes to the cytoskeletal actin and organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered and adopts an autoinhibited conformation, which prevents CD44ct from binding directly to activated Ezrin in solution. Binding to the signaling lipid phosphatidylinositol 4,5-biphosphlate (PIP2) disrupts autoinhibition in CD44ct, and activates CD44ct to associate with Ezrin. Further, using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific hetero-tetramer complex of CD44ct with Ezrin. This study reveals a novel autoregulation mechanism in the cytoplasmic tail of CD44 and the role of PIP2 in mediating the assembly of multimeric CD44ct-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of multimeric PIP2-CD44-Ezrin complexes.

  20. Microstructure of oxide dispersion strengthened Eurofer and iron-chromium alloys investigated by means of small-angle neutron scattering and transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Heintze, C.; Bergner, F.; Ulbricht, A.; Hernández-Mayoral, M.; Keiderling, U.; Lindau, R.; Weissgärber, T.

    2011-09-01

    Oxide dispersion strengthening of ferritic/martensitic chromium steels is a promising route for the extension of the range of operation temperatures for nuclear applications. The investigation of dedicated model alloys is an important means in order to separate individual effects contributing to the mechanical behaviour under irradiation and to improve mechanistic understanding. A powder metallurgy route based on spark plasma sintering was applied to fabricate oxide dispersion strengthened (ODS) Fe9Cr model materials. These materials along with Eurofer97 and ODS-Eurofer were investigated by means of small-angle neutron scattering (SANS) and TEM. For Fe9Cr-0.6 wt.%Y 2O 3, TEM results indicate a peak radius of the size distribution of Y 2O 3 particles of 4.2 nm with radii ranging up to 15 nm, and a volume fraction of 0.7%, whereas SANS indicates a peak radius of 3.8 nm and a volume fraction of 0.6%. It was found that the non-ODS Fe9Cr and Eurofer97 are suitable reference materials for ODS-Fe9Cr and ODS-Eurofer, respectively, and that the ODS-Fe9Cr variants are suitable model materials for the separated investigation of irradiation-Y 2O 3 particle interaction effects.

  1. Characterization of nanostructured zirconia prepared by hydrolysis and reverse micelle synthesis by small-angle neutron and X-ray scattering

    SciTech Connect

    Thiyagarajan, P.; Li, X.; Littrell, K.; Seifert, S.; Csencsits, R.; Loong, C.

    1999-12-07

    Low temperature techniques such as hydrolysis and reverse micelle syntheses provide the opportunity to determine the relationship between the structural properties and preparation conditions of zirconia powders as well as to tailor their physicochemical properties. The authors have performed small-angle neutron and synchrotron X-ray scattering (SANS and SAXS) experiments to study the nucleation and organization of zirconia nanoparticles via different preparation routes. First, the formation of reverse micelles in individual and mixed solutions of (ZrOCl{sub 2}+D{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3}, and (NH{sub 4}OH+H{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3} systems at water/AOT molar ratio of 20 was characterized. Second, the aggregation of zirconia gels obtained from the reaction of the reverse micelle solutions after heat treatments was studied. Third, the nanostructure of zirconia powders prepared by the reverse micelle method is compared with the corresponding powders prepared by hydrolysis after different heat treatments.

  2. Small-Angle Neutron Scattering Reveals pH-Dependent Conformational Changes in Trichoderma reesei Cellobiohydrolase I: Implications for Enzymatic Activity

    SciTech Connect

    Pingali, Sai Venkatesh; O'Neill, Hugh Michael; McGaughey, Joseph; Urban, Volker S; Rempe, Caroline S; Petridis, Loukas; Smith, Jeremy C; Evans, Barbara R; Heller, William T

    2011-01-01

    Cellobiohydrolase I (Cel7A) of the fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) hydrolyzes crystalline cellulose to soluble sugars, making it of key interest for producing fermentable sugars from biomass for biofuel production. The activity of the enzyme is pH-dependent, with its highest activity occurring at pH 4 5. To probe the response of the solution structure of Cel7A to changes in pH, we measured small angle neutron scattering of it in a series of solutions having pH values of 7.0, 6.0, 5.3, and 4.2. As the pH decreases from 7.0 to 5.3, the enzyme structure remains well defined, possessing a spatial differentiation between the cellulose binding domain and the catalytic core that only changes subtly. At pH 4.2, the solution conformation of the enzyme changes to a structure that is intermediate between a properly folded enzyme and a denatured, unfolded state, yet the secondary structure of the enzyme is essentially unaltered. The results indicate that at the pH of optimal activity, the catalytic core of the enzyme adopts a structure in which the compact packing typical of a fully folded polypeptide chain is disrupted and suggest that the increased range of structures afforded by this disordered state plays an important role in the increased activity of Cel7A through conformational selection.

  3. Structural characterization of the circadian clock protein complex composed of KaiB and KaiC by inverse contrast-matching small-angle neutron scattering

    PubMed Central

    Sugiyama, Masaaki; Yagi, Hirokazu; Ishii, Kentaro; Porcar, Lionel; Martel, Anne; Oyama, Katsuaki; Noda, Masanori; Yunoki, Yasuhiro; Murakami, Reiko; Inoue, Rintaro; Sato, Nobuhiro; Oba, Yojiro; Terauchi, Kazuki; Uchiyama, Susumu; Kato, Koichi

    2016-01-01

    The molecular machinery of the cyanobacterial circadian clock consists of three proteins: KaiA, KaiB, and KaiC. Through interactions among the three Kai proteins, the phosphorylation states of KaiC generate circadian oscillations in vitro in the presence of ATP. Here, we characterized the complex formation between KaiB and KaiC using a phospho-mimicking mutant of KaiC, which had an aspartate substitution at the Ser431 phosphorylation site and exhibited optimal binding to KaiB. Mass-spectrometric titration data showed that the proteins formed a complex exclusively in a 6:6 stoichiometry, indicating that KaiB bound to the KaiC hexamer with strong positive cooperativity. The inverse contrast-matching technique of small-angle neutron scattering enabled selective observation of KaiB in complex with the KaiC mutant with partial deuteration. It revealed a disk-shaped arrangement of the KaiB subunits on the outer surface of the KaiC C1 ring, which also serves as the interaction site for SasA, a histidine kinase that operates as a clock-output protein in the regulation of circadian transcription. These data suggest that cooperatively binding KaiB competes with SasA with respect to interaction with KaiC, thereby promoting the synergistic release of this clock-output protein from the circadian oscillator complex. PMID:27752127

  4. Vortex lattice structure in BaFe2(As0.67P0.33)2 via small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Morisaki-Ishii, R.; Kawano-Furukawa, H.; Cameron, A. S.; Lemberger, L.; Blackburn, E.; Holmes, A. T.; Forgan, E. M.; DeBeer-Schmitt, L. M.; Littrell, K.; Nakajima, M.; Kihou, K.; Lee, C. H.; Iyo, A.; Eisaki, H.; Uchida, S.; White, J. S.; Dewhurst, C. D.; Gavilano, J. L.; Zolliker, M.

    2014-09-01

    We have observed a magnetic vortex lattice (VL) in BaFe2(As0.67P0.33)2 (BFAP) single crystals by small-angle neutron scattering. With the field along the c axis, a nearly isotropic hexagonal VL was formed in the field range from 1 to 16 T, and no symmetry changes in the VL were observed. The temperature dependence of the VL signal was measured and confirms the presence of (non-d-wave) nodes in the superconducting gap structure for measurements at 5 T and below. The nodal effects were suppressed at high fields. At low fields, a VL reorientation transition was observed between 1 and 3 T, with the VL orientation changing by 45∘. Below 1 T, the VL structure was strongly affected by pinning and the diffraction pattern had a fourfold symmetry. We suggest that this (and possibly also the VL reorientation) is due to pinning to defects aligned with the crystal structure, rather than being intrinsic. The temperature dependence of the scaled intensity suggests that BFAP possesses at least one full gap and one nodal gap with circular symmetry. Judging from the symmetry, the node structure should take the form of an "accidental" circular line node, which is consistent with recent angle-resolved photoemission spectroscopy results [Y. Zhang, Z. R. Ye, Q. Q. Ge, F. Chen, J. Jiang, M. Xu, B. P. Xie, and D. L. Feng, Nature Physics 8, 371 (2012)., 10.1038/nphys2248].

  5. Effect of urea on heat-induced gelation of bovine serum albumin (BSA) studied by rheology and small angle neutron scattering (SANS)

    NASA Astrophysics Data System (ADS)

    Nnyigide, Osita Sunday; Oh, Yuna; Song, Hyeong Yong; Park, Eun-kyoung; Choi, Soo-Hyung; Hyun, Kyu

    2017-05-01

    This paper reports the effects of urea on the heat-induced gelation of bovine serum albumin (BSA), which was studied by the tube inversion method, rheological measurements, and small-angle neutron scattering (SANS). An increase in the urea concentration accelerated the rate of gelation because the protein molecules have already been unfolded to some extent during sample preparation in the urea solution. In addition, the BSA solution in the presence of urea underwent a sol-gel-sol transition during the time sweep test at a constant temperature of 80oC. On the other hand, the BSA solution without urea turned into a hard and brittle gel that did not return to the solution state during isothermal heating at a constant temperature of 80oC. Aggregation and re-bonding of the denatured and unfolded protein chains led to gel formation. Urea added to the protein denatures its tertiary and secondary structures by simultaneously disrupting the hydrogen bonds, hydrophobic interactions, and altering the solvent properties. Furthermore, urea induces thermoreversible chemical interactions in BSA solutions leading to the formation of a gel with dynamic properties under these experimental conditions.

  6. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering*

    PubMed Central

    Chen, Xiaodong; Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; Stanley, Christopher B.; Do, Changwoo; Heller, William T.; Aggarwal, Aneel K.; Callaway, David J. E.; Bu, Zimei

    2015-01-01

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin that links the CD44 assembled receptor signaling complexes to the cytoskeletal actin network, which organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered. Upon binding to the signaling lipid phosphatidylinositol 4,5-bisphosphate (PIP2), CD44ct clusters into aggregates. Further, contrary to the generally accepted model, CD44ct does not bind directly to the FERM domain of Ezrin or to the full-length Ezrin but only forms a complex with FERM or with the full-length Ezrin in the presence of PIP2. Using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific heterotetramer complex of CD44ct with Ezrin. This study reveals the role of PIP2 in clustering CD44 and in assembling multimeric CD44-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of CD44 clusters and the multimeric PIP2-CD44-Ezrin complexes. PMID:25572402

  7. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    NASA Astrophysics Data System (ADS)

    Putra, Edy Giri Rachman; Patriati, Arum

    2015-04-01

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2-10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30-50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  8. Determination of the structure of the organized phase of the block copolymer PEO-PPO-PEO in aqueous solutions under flow by small-angle neutron scattering.

    PubMed

    Perreur, Christelle; Habas, Jean-Pierre; François, Jeanne; Peyrelasse, Jean; Lapp, Alain

    2002-04-01

    The organization of Tetronic 908 (T908), a star copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) blocks, has been examined. Above critical conditions of temperature and concentration, the micelles formed by the aggregation of PPO units self-organize into particular structures. While small-angle neutron scattering (SANS) characterizations performed with static conditions demonstrate the organization of the medium, the experimental results do not allow us to make a distinction between simple cubic and body-centered-cubic structures. However, SANS measurements realized under shear produce characteristic diffraction diagrams. In this paper, an accurate methodology is proposed to identify, without ambiguity, the exact nature of the organized phase. Applied to our system, indexing of the diffraction pattern spots reveals that the organization of T908 is of bcc type oriented with the [111] direction parallel to the direction of flow, but the crystals can present any orientation about this direction. The lattice size has been estimated and compared to previous published results.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  10. Effects of N,N-dimethyl-N-alkylamine-N-oxides on DOPC bilayers in unilamellar vesicles: small-angle neutron scattering study.

    PubMed

    Belička, Michal; Kučerka, Norbert; Uhríková, Daniela; Islamov, Akhmed Kh; Kuklin, Alexander I; Devínsky, Ferdinand; Balgavý, Pavol

    2014-05-01

    Small-angle neutron scattering data were collected from aqueous dispersions of unilamellar vesicles (ULVs) consisting of mixtures of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine and a homologous series of N,N-dimethyl-N-alkylamine-N-oxides (CnNO, n = 12, 14, 16, and 18, where n is the number of carbon atoms in the alkyl chain). A modeling approach was applied to the neutron scattering curves to obtain the bilayer structural parameters. Particularly, the external (2)H2O/H2O contrast variation technique was carried out on pure dioleoylphosphatidylcholine (DOPC) ULVs to determine the hydrophilic region thickness [Formula: see text] = 9.8 ± 0.6 Å. Consequently, the hydrocarbon region thickness [Formula: see text], the lateral bilayer area per one lipid molecule [Formula: see text], and the number of water molecules located in the hydrophilic region per one lipid molecule [Formula: see text] were obtained from single-contrast neutron scattering curves using the previously determined [Formula: see text]. The structural parameters were extracted as functions of [Formula: see text] (the CnNO:DOPC molar ratio) and n. The dependences [Formula: see text] provided the partial lateral areas of CnNOs ([Formula: see text]) and DOPC ([Formula: see text]) in bilayers. It was observed that the [Formula: see text]'s were constant in the investigated interval of [Formula: see text] and for n = 12, 14, and 16 equal to 36.6 ± 0.4 Å(2), while [Formula: see text] increased to 39.4 ± 0.4 Å(2). The bilayer hydrocarbon region thickness [Formula: see text] decreased with intercalation of each CnNO. This effect increased with [Formula: see text] and decreased with increasing CnNO alkyl chain length. The intercalation of C18NO changed the [Formula: see text] only slightly. To quantify the effect of CnNO intercalation into DOPC bilayers we fit the [Formula: see text] dependences with weighted linear approximations and acquired their slopes [Formula: see text].

  11. Characterization of the Decaheme c-Type Cytochrome OmcA in Solution and on Hematite Surfaces by Small Angle X-Ray Scattering and Neutron Reflectometry

    SciTech Connect

    Johs, A.; Shi, L.; Droubay, T.; Ankner, J. F.; Liang, L.

    2010-06-15

    The outer membrane protein OmcA is an 85 kDa decaheme c-type cytochrome located on the surface of the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. It is assumed to mediate shuttling of electrons to extracellular acceptors that include solid metal oxides such as hematite (α-Fe2O3). No information is yet available concerning OmcA structure in physiologically relevant conditions such as aqueous environments. We purified OmcA and characterized its solution structure by small angle x-ray scattering (SAXS), and its interaction at the hematite-water interface by neutron reflectometry. SAXS showed that OmcA is a monomer that adopts a flat ellipsoidal shape with an overall dimension of 34 × 90 × 65 Å3. To our knowledge, we obtained the first direct evidence that OmcA undergoes a redox state-dependent conformational change in solution whereby reduction decreases the overall length of OmcA by ~7 Å (the maximum dimension was 96 Å for oxidized OmcA, and 89 Å for NADH and dithionite-reduced OmcA). OmcA was also found to physically interact with electron shuttle molecules such as flavin mononucleotide, resulting in the formation of high-molecular-weight assemblies. Neutron reflectometry showed that OmcA forms a well-defined monomolecular layer on hematite surfaces, where it assumes an orientation that maximizes its contact area with the mineral surface. Finally, these novel insights into the molecular structure of OmcA in solution, and its interaction with insoluble hematite and small organic ligands, demonstrate the fundamental structural bases underlying OmcA's role in mediating redox processes.

  12. Characterization of the decaheme c-type cytochrome OmcA in solution and on hematite surfaces by small angle x-ray scattering and neutron reflectometry.

    PubMed

    Johs, A; Shi, L; Droubay, T; Ankner, J F; Liang, L

    2010-06-16

    The outer membrane protein OmcA is an 85 kDa decaheme c-type cytochrome located on the surface of the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. It is assumed to mediate shuttling of electrons to extracellular acceptors that include solid metal oxides such as hematite (alpha-Fe(2)O(3)). No information is yet available concerning OmcA structure in physiologically relevant conditions such as aqueous environments. We purified OmcA and characterized its solution structure by small angle x-ray scattering (SAXS), and its interaction at the hematite-water interface by neutron reflectometry. SAXS showed that OmcA is a monomer that adopts a flat ellipsoidal shape with an overall dimension of 34 x 90 x 65 A(3). To our knowledge, we obtained the first direct evidence that OmcA undergoes a redox state-dependent conformational change in solution whereby reduction decreases the overall length of OmcA by approximately 7 A (the maximum dimension was 96 A for oxidized OmcA, and 89 A for NADH and dithionite-reduced OmcA). OmcA was also found to physically interact with electron shuttle molecules such as flavin mononucleotide, resulting in the formation of high-molecular-weight assemblies. Neutron reflectometry showed that OmcA forms a well-defined monomolecular layer on hematite surfaces, where it assumes an orientation that maximizes its contact area with the mineral surface. These novel insights into the molecular structure of OmcA in solution, and its interaction with insoluble hematite and small organic ligands, demonstrate the fundamental structural bases underlying OmcA's role in mediating redox processes. (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  13. Characterization of the Decaheme c-Type Cytochrome OmcA in Solution and on Hematite Surfaces by Small Angle X-Ray Scattering and Neutron Reflectometry

    PubMed Central

    Johs, A.; Shi, L.; Droubay, T.; Ankner, J.F.; Liang, L.

    2010-01-01

    Abstract The outer membrane protein OmcA is an 85 kDa decaheme c-type cytochrome located on the surface of the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. It is assumed to mediate shuttling of electrons to extracellular acceptors that include solid metal oxides such as hematite (α-Fe2O3). No information is yet available concerning OmcA structure in physiologically relevant conditions such as aqueous environments. We purified OmcA and characterized its solution structure by small angle x-ray scattering (SAXS), and its interaction at the hematite-water interface by neutron reflectometry. SAXS showed that OmcA is a monomer that adopts a flat ellipsoidal shape with an overall dimension of 34 × 90 × 65 Å3. To our knowledge, we obtained the first direct evidence that OmcA undergoes a redox state-dependent conformational change in solution whereby reduction decreases the overall length of OmcA by ∼7 Å (the maximum dimension was 96 Å for oxidized OmcA, and 89 Å for NADH and dithionite-reduced OmcA). OmcA was also found to physically interact with electron shuttle molecules such as flavin mononucleotide, resulting in the formation of high-molecular-weight assemblies. Neutron reflectometry showed that OmcA forms a well-defined monomolecular layer on hematite surfaces, where it assumes an orientation that maximizes its contact area with the mineral surface. These novel insights into the molecular structure of OmcA in solution, and its interaction with insoluble hematite and small organic ligands, demonstrate the fundamental structural bases underlying OmcA's role in mediating redox processes. PMID:20550916

  14. Small-Angle Scattering from Nanoscale Fat Fractals.

    PubMed

    Anitas, E M; Slyamov, A; Todoran, R; Szakacs, Z

    2017-12-01

    Small-angle scattering (of neutrons, x-ray, or light; SAS) is considered to describe the structural characteristics of deterministic nanoscale fat fractals. We show that in the case of a polydisperse fractal system, with equal probability for any orientation, one obtains the fractal dimensions and scaling factors at each structural level. This is in agreement with general results deduced in the context of small-angle scattering analysis of a system of randomly oriented, non-interacting, nano-/micro-fractals. We apply our results to a two-dimensional fat Cantor-like fractal, calculating analytic expressions for the scattering intensities and structure factors. We explain how the structural properties can be computed from experimental data and show their correlation to the variation of the scaling factor with the iteration number. The model can be used to interpret recorded experimental SAS data in the framework of fat fractals and can reveal structural properties of materials characterized by a regular law of changing of the fractal dimensions. It can describe successions of power-law decays, with arbitrary decreasing values of the scattering exponents, and interleaved by regions of constant intensity.

  15. Small-Angle Scattering from Nanoscale Fat Fractals

    NASA Astrophysics Data System (ADS)

    Anitas, E. M.; Slyamov, A.; Todoran, R.; Szakacs, Z.

    2017-06-01

    Small-angle scattering (of neutrons, x-ray, or light; SAS) is considered to describe the structural characteristics of deterministic nanoscale fat fractals. We show that in the case of a polydisperse fractal system, with equal probability for any orientation, one obtains the fractal dimensions and scaling factors at each structural level. This is in agreement with general results deduced in the context of small-angle scattering analysis of a system of randomly oriented, non-interacting, nano-/micro-fractals. We apply our results to a two-dimensional fat Cantor-like fractal, calculating analytic expressions for the scattering intensities and structure factors. We explain how the structural properties can be computed from experimental data and show their correlation to the variation of the scaling factor with the iteration number. The model can be used to interpret recorded experimental SAS data in the framework of fat fractals and can reveal structural properties of materials characterized by a regular law of changing of the fractal dimensions. It can describe successions of power-law decays, with arbitrary decreasing values of the scattering exponents, and interleaved by regions of constant intensity.

  16. Small-angle neutron scattering study of magnetic ordering and inhomogeneity across the martensitic phase transformation in Ni50–xCoxMn₄₀Sn₁₀ alloys

    DOE PAGES

    Bhatti, Kanwal Preet; El-Khatib, S.; Srivastava, Vijay; ...

    2012-04-27

    The Heusler-derived multiferroic alloy Ni50–xCoxMn₄₀Sn₁₀ has recently been shown to exhibit, at just above room temperature, a highly reversible martensitic phase transformation with an unusually large magnetization change. In this work the nature of the magnetic ordering above and below this transformation has been studied in detail in the critical composition range x = 6–8 via temperature-dependent (5–600 K) magnetometry and small-angle neutron scattering (SANS). We observe fairly typical paramagnetic to long-range-ordered ferromagnetic phase transitions on cooling to 420–430 K, with the expected critical spin fluctuations, followed by first-order martensitic phase transformations to a nonferromagnetic state below 360–390 K. Themore » static magnetization reveals complex magnetism in this low-temperature nonferromagnetic phase, including a Langevin-like field dependence, distinct spin freezing near 60 K, and significant exchange bias effects, consistent with superparamagnetic blocking of ferromagnetic clusters of nanoscopic dimensions. We demonstrate that these spin clusters, whose existence has been hypothesized in a variety of martensitic alloys exhibiting competition between ferromagnetic and antiferromagnetic exchange interactions, can be directly observed by SANS. The scattering data are consistent with a liquidlike spatial distribution of interacting magnetic clusters with a mean center-to-center spacing of 12 nm. Considering the behavior of the superparmagnetism, cooling-field and temperature-dependent exchange bias, and magnetic SANS, we discuss in detail the physical form and origin of these spin clusters, their intercluster interactions, the nature of the ground-state magnetic ordering in the martensitic phase, and the implications for our understanding of such alloy systems.« less

  17. Analysis of PKR Structure by Small-Angle Scattering

    SciTech Connect

    VanOudenhove, Jennifer; Anderson, Eric; Krueger, Susan; Cole, James L.

    2009-04-27

    Protein kinase R (PKR) is a key component of the interferon antiviral defense pathway. Upon binding double-stranded RNA, PKR undergoes autophosphorylation reactions that activate the kinase. PKR contains an N-terminal double-stranded RNA binding domain, which consists of two tandem double-stranded RNA binding motifs, and a C-terminal kinase domain. We have used small-angle X-ray scattering and small-angle neutron scattering to define the conformation of latent PKR in solution. Guinier analysis indicates a radius of gyration of about 35 {angstrom}. The p(r) distance distribution function exhibits a peak near 30 {angstrom}, with a broad shoulder extending to longer distances. Good fits to the scattering data require models that incorporate multiple compact and extended conformations of the two interdomain linker regions. Thus, PKR belongs to the growing family of proteins that contain intrinsically unstructured regions. We propose that the flexible linkers may allow PKR to productively dimerize upon interaction with RNA activators that have diverse structures.

  18. Droplet polydispersity and shape fluctuations in AOT [bis(2-ethylhexyl)sulfosuccinate sodium salt] microemulsions studied by contrast variation small-angle neutron scattering

    SciTech Connect

    Arleth, Lise; Pedersen, Jan Skov

    2001-06-01

    Microemulsions consisting of AOT water, and decane or iso-octane are studied in the region of the phase diagram where surfactant covered water droplets are formed. The polydispersity and shape fluctuations of the microemulsion droplets are determined and compared in the two different alkane types. Conductivity measurements show that there is a pronounced dependence of the temperature behavior of the microemulsion on the type of alkane used. In both cases the microemulsion droplets start to form larger aggregates when the temperature increases. But in the system with decane this aggregation temperature occurs at a temperature about 10{degree}C lower than in a similar system with iso-octane. Aggregation phenomena are avoided and the two systems are at approximately the same reduced temperature with respect to the aggregation temperature when the temperature of the AOT/D{sub 2}O/decane microemulsion is 10{degree}C and the temperature of the AOT/D{sub 2}O/iso-octane microemulsion is 20{degree}C. Contrast variation small-angle neutron scattering measurements are performed at these temperatures on systems with volume fractions of 5% D{sub 2}O+AOT by varying the scattering length density of the alkane. The small-angle scattering for 11 different contrasts evenly distributed around the match points are studied for each sample. The scattering data for the different contrasts are analyzed using a molecular constrained model for ellipsoidal droplets of water covered by AOT, interacting as polydisperse hard spheres. All contrasts are fitted simultaneously by taking the different contrast factors into account. The analysis show that at the same reduced temperature with respect to the aggregation temperature the droplet size, polydispersity index, the size of the shape fluctuations are similar in the two systems. A polydispersity index ({sigma}/R of the Gaussian size distribution) of 16% and an average axis ratio of the droplets of 1.56 is found in the AOT/D{sub 2}O

  19. Pore characteristics and their emergent effect on water adsorption and transport in clays using small-angle neutron scattering with contrast variation

    NASA Astrophysics Data System (ADS)

    Ding, M.; Hartl, M.; Wang, Y.; Hjelm, R.

    2013-12-01

    In nuclear waste management, clays are canonical materials in the construction of engineered barriers. They are also naturally occurring reactive minerals which play an important role in retention and colloidal facilitated reactive transport in subsurface systems. Knowledge of total and accessible porosity in clays is crucial in determining fluids transport behavior in clays. It will provide fundamental insight on the performance efficiency of specific clays as a barrier material and their role in regulating radionuclide transport in subsurface environments. The aim of the present work is to experimentally investigate the change in pore characteristics of clays as function of moisture content, and to determine their pore character in relation to their water retention capacity. Recent developments in small-angle neutron scattering (SANS) techniques allow quantitative measurement of pore morphology and size distribution of various materials in their pristine state under various sample environments (exposure to solution, high temperature, and so on). Furthermore, due to dramatic different neutron scattering properties of hydrogen and deuterium, one can readily use contrast variation, which is the isotopic labeling with various ratios of H and D (e.g. mixture of H2O/D2O) to highlight or suppress features of the sample. This is particularly useful in the study of complex pore system such as clays. In this study, we have characterized the pore structures for a number of clays including clay minerals and field samples which are relevant to high-level waste systems under various sample environments (e.g., humidity, temperature and pressure) using SANS. Our results suggest that different clays show unique pore features under various sample environments. To distinguish between accessible/non-accessible pores and the nature of pore filling (e.g. the quantity of H2O adsorbed by clays, and the distribution of H2O in relation to pore character) to water, clays were exposed for

  20. Application of X-ray and neutron small angle scattering techniques to study the hierarchical structure of plant cell walls: a review.

    PubMed

    Martínez-Sanz, Marta; Gidley, Michael J; Gilbert, Elliot P

    2015-07-10

    Plant cell walls present an extremely complex structure of hierarchically assembled cellulose microfibrils embedded in a multi-component matrix. The biosynthesis process determines the mechanism of cellulose crystallisation and assembly, as well as the interaction of cellulose with other cell wall components. Thus, a knowledge of cellulose microfibril and bundle architecture, and the structural role of matrix components, is crucial for understanding cell wall functional and technological roles. Small angle scattering techniques, combined with complementary methods, provide an efficient approach to characterise plant cell walls, covering a broad and relevant size range while minimising experimental artefacts derived from sample treatment. Given the system complexity, approaches such as component extraction and the use of plant cell wall analogues are typically employed to enable the interpretation of experimental results. This review summarises the current research status on the characterisation of the hierarchical structure of plant cell walls using small angle scattering techniques.

  1. Small-angle scattering study of Aspergillus awamori glycoprotein glucoamylase

    NASA Astrophysics Data System (ADS)

    Schmidt, A. E.; Shvetsov, A. V.; Kuklin, A. I.; Lebedev, D. V.; Surzhik, M. A.; Sergeev, V. R.; Isaev-Ivanov, V. V.

    2016-01-01

    Glucoamylase from fungus Aspergillus awamori is glycoside hydrolase that catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic bonds in glucose polymers and oligomers. This glycoprotein consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated polypeptide chain. The conformation of the linker, the relative arrangement of the domains, and the structure of the full-length enzyme are unknown. The structure of the recombinant glucoamylase GA1 was studied by molecular modelling and small-angle neutron scattering (SANS) methods. The experimental SANS data provide evidence that glucoamylase exists as a monomer in solution and contains a glycoside component, which makes a substantial contribution to the scattering. The model of full-length glucoamylase, which was calculated without taking into account the effect of glycosylation, is consistent with the experimental data and has a radius of gyration of 33.4 ± 0.6 Å.

  2. Small angle scattering from protein/sugar conjugates

    NASA Astrophysics Data System (ADS)

    Jackson, Andrew; White, John

    2006-11-01

    The Maillard reaction between free amine groups on proteins and sugars is well known. We have examined the effect of the reaction of the casein group of milk proteins with sugars on their nanoscale structure and aggregation. The small angle neutron scattering from beta casein and sodium caseinate and their sugar conjugates have been studied as a function of solution concentration. At high conjugate concentration (greater than ca. 5 mg/ml) the addition of sugar reduces supra-micellar aggregation of the protein whilst at lower concentration, where the protein is expected to be deaggregated already, little effect is seen. Guinier analysis of the scattering data show a radius of gyration of around 75 A˚ for beta casein in solution and around 80 A˚ for the sucrose conjugate.

  3. Small-angle scattering study of Aspergillus awamori glycoprotein glucoamylase

    SciTech Connect

    Schmidt, A. E. Shvetsov, A. V.; Kuklin, A. I.; Lebedev, D. V.; Surzhik, M. A.; Sergeev, V. R.; Isaev-Ivanov, V. V.

    2016-01-15

    Glucoamylase from fungus Aspergillus awamori is glycoside hydrolase that catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic bonds in glucose polymers and oligomers. This glycoprotein consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated polypeptide chain. The conformation of the linker, the relative arrangement of the domains, and the structure of the full-length enzyme are unknown. The structure of the recombinant glucoamylase GA1 was studied by molecular modelling and small-angle neutron scattering (SANS) methods. The experimental SANS data provide evidence that glucoamylase exists as a monomer in solution and contains a glycoside component, which makes a substantial contribution to the scattering. The model of full-length glucoamylase, which was calculated without taking into account the effect of glycosylation, is consistent with the experimental data and has a radius of gyration of 33.4 ± 0.6 Å.

  4. Growth kinetics of lipid-based nanodiscs to unilamellar vesicles-a time-resolved small angle neutron scattering (SANS) study.

    PubMed

    Mahabir, Suanne; Small, Darcy; Li, Ming; Wan, Wankei; Kučerka, Norbert; Littrell, Kenneth; Katsaras, John; Nieh, Mu-Ping

    2013-03-01

    Mixtures of dimyristoyl-phosphatidylcholine (DMPC), dimyristoyl-phosphatidylglycerol (DMPG) and dihexanoyl-phosphatidylcholine (DHPC) in aqueous solutions spontaneously form monodisperse, bilayered nanodiscs (also known as "bicelles") at or below the melting transition temperature of DMPC (T(M) ~23°C). In dilute systems above the main transition temperature T(M) of DMPC, bicelles coalesce (increasing their diameter) and eventually self-fold into unilamellar vesicles (ULVs). Time-resolved small angle neutron scattering was used to study the growth kinetics of nanodiscs below and equal to T(M) over a period of hours as a function of temperature at two lipid concentrations in presence or absence of NaCl salt. Bicelles seem to undergo a sudden initial growth phase with increased temperature, which is then followed by a slower reaction-limited growth phase that depends on ionic strength, lipid concentration and temperature. The bicelle interaction energy was derived from the colloidal theory of Derjaguin and Landau, and Verwey and Overbeek (DLVO). While the calculated total energy between discs is attractive and proportional to their growth rate, a more detailed mechanism is proposed to describe the mechanism of disc coalescence. After annealing at low temperature (low-T), samples were heated to 50°C in order to promote the formation of ULVs. Although the low-T annealing of samples has only a marginal effect on the mean size of end-state ULVs, it does affect their polydispersity, which increases with increased T, presumably driven by the entropy of the system. Published by Elsevier B.V.

  5. Pore Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir Pressure-Temperature Conditions Using Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.

    2015-12-01

    Oil/gas produced from unconventional reservoirs has become strategically important for the US domestic energy independence. In unconventional realm, hydrocarbons are generated and stored in nanopores media ranging from a few to hundreds of nanometers. Fundamental knowledge of coupled thermo-hydro-mechanical-chemical (THMC) processes that control fluid flow and propagation within nano-pore confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer pores creates many complex rock-fluid interface interactions. It is imperative to promote innovative experimental studies to decipher physical and chemical processes at the nanopore scale that govern hydrocarbon generation and mass transport of hydrocarbon mixtures in tight shale and other low permeability formations at reservoir pressure-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between pore characteristics of the Wolfcamp shale from Western Texas and the shale interaction with fluids at reservoir P-T conditions using small-angle neutron scattering (SANS). We have performed SANS measurements of the shale rock in single fluid (e.g., H2O and D2O) and multifluid (CH4/(30% H2O+70% D2O)) systems at various pressures up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different pressures with H2O as the pressure medium. Our data analysis using IRENA software suggests that the principal changes of pore volume in the shale occurred on smaller than 50 nm pores and pressure at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into pores; with decreasing P, water is retained in the pores.

  6. Effect of Protein Incorporation on the Nanostructure of the Bicontinuous Microemulsion Phase of Winsor-III Systems: A Small-Angle Neutron Scattering Study

    DOE PAGES

    Hayes, Douglas G.; Gomez del Rio, Javier A.; Ye, Ran; ...

    2015-01-20

    Small-angle neutron scattering (SANS) analysis using the Teubner₋Strey model has been employed to evaluate the effect of protein incorporation into the middle, bicontinuous microemulsion (BμE) phase of Winsor-III (WIII) systems formed by an aerosol-OT (AOT)/alkyl ethoxylate mixed surfactant system to understand better the extraction of proteins into and out of BμEs and to study the effect of proteins on a system that serves as a biomimetic analog of cell membranes. Under conditions of high salinity, the incorporation of positively charged proteins cytochrome c, lysozyme, and α-chymotrypsin, near their solubilization limit in the BμEs promoted the release of water and oilmore » from the BμEs, a decrease in the quasi-periodic repeat distance (d), an increase in ordering (a decrease in the amphiphilicity factor, fa) for the surfactant monolayers, and a decrease in the surface area per surfactant headgroup, suggesting that the proteins affected the self-assembly of components in the BμE phase and produced Debye shielding of AOTs sulfonate headgroup. For WIII systems possessing lower salinity, cytochrome c reduced the efficiency of surfactant in the BμE phase, noted by increases in d and fa, suggesting that the enzyme and AOT underwent ion pairing. We find that the results of this study demonstrate the importance of ionic strength to modulate proteinsurfactant interactions, which in turn will control the release of proteins encapsulated in the BμEs, relevant to WIII-based protein extraction and controlled release from BμE delivery systems, and demonstrate the utility of BμEs as a model system to understand the effect of proteins on biomembranes.« less

  7. Deuterium Labeling Together with Contrast Variation Small-Angle Neutron Scattering Suggests How Skp Captures and Releases Unfolded Outer Membrane Proteins.

    PubMed

    Zaccai, Nathan R; Sandlin, Clifford W; Hoopes, James T; Curtis, Joseph E; Fleming, Patrick J; Fleming, Karen G; Krueger, Susan

    2016-01-01

    In Gram-negative bacteria, the chaperone protein Skp forms specific and stable complexes with membrane proteins while they are transported across the periplasm to the outer membrane. The jellyfish-like architecture of Skp is similar to the eukaryotic and archaeal prefoldins and the mitochondrial Tim chaperones, that is the α-helical "tentacles" extend from a β-strand "body" to create an internal cavity. Contrast variation small-angle neutron scattering (SANS) experiments on Skp alone in solution and bound in two different complexes to unfolded outer membrane proteins (uOMPs), OmpA and OmpW, demonstrate that the helical tentacles of Skp bind their substrate in a clamp-like mechanism in a conformation similar to that previously observed in the apo crystal structure of Skp. Deuteration of the uOMP component combined with contrast variation analysis allowed the shapes of Skp and uOMP as well as the location of uOMP with respect to Skp to be determined in both complexes. This represents unique information that could not be obtained without deuterium labeling of the uOMPs. The data yield the first direct structural evidence that the α-helical Skp tentacles move closer together on binding its substrate and that the structure of Skp is different when binding different uOMPs. This work presents, by example, a tutorial on performing SANS experiments using both deuterium labeling and contrast variation, including SANS theory, sample preparation, data collection, sample quality validation, data analysis, and structure modeling.

  8. Small-angle neutron scattering studies of mineralization on BSA coated citrate capped gold nanoparticles used as a model surface for membrane scaling in RO wastewater desalination.

    PubMed

    Dahdal, Y N; Pipich, V; Rapaport, H; Oren, Y; Kasher, R; Schwahn, D

    2014-12-23

    Bovine serum albumin (BSA) coated on citrate capped gold nanoparticles (BSA-GNPs) was exposed to a simulated wastewater effluent (SSE) in order to study the mineralization and thereby mimic scaling at biofouled membranes of reverse osmosis (RO) wastewater desalination plants. RO is a leading technology of achieving freshwater quality as it has the capability of removing both dissolved inorganic salts and organic contaminants from tertiary wastewater effluents. The aim was to better understand one of the major problems facing this technology which is fouling of the membranes, mainly biofouling and scaling by calcium phosphate. The experiments were performed using the small-angle neutron scattering (SANS) technique. The nanoparticles, GNPs, stabilized by the citrate groups showed 30 Å large particles having a homogeneous distribution of gold and citrate with a gold volume fraction of the order of 1%. On the average two BSA monomers are grafted at 2.4 GNPs. The exposed BSA-GNPs to SSE solution led to immediate mineralization of stable composite particles of the order of 0.2 μm diameter and a mineral volume fraction between 50% and 80%. The volume fraction of the mineral was of the order of 10(-5), which is roughly 3 times larger but an order of magnitude smaller than the maximum possible contents of respectively calcium phosphate and calcium carbonate in the SSE solution. Considering the extreme low solubility product of calcium phosphate, we suggest total calcium phosphate and partially (5-10%) calcium carbonate formation in the presence of BSA-GNPs.

  9. Multi-scale characterization of pore evolution in a combustion metamorphic complex, Hatrurim basin, Israel: Combining (ultra) small-angle neutron scattering and image analysis

    SciTech Connect

    Wang, Hsiu-Wen; Anovitz, Lawrence {Larry} M; Burg, Avihu; Cole, David; Allard Jr, Lawrence Frederick; Jackson, Andrew J; Stack, Andrew G; Rother, Gernot; Ciarlette, Diane D

    2013-01-01

    Backscattered scanning electron micrograph and ultra small- and small-angle neutron scattering data have been combined to provide statistically meaningful data on the pore/grain structure and pore evolution of combustion metamorphic complexes from the Hatrurim basin, Israel. Three processes, anti-sintering roughening, alteration of protolith (dehydration, decarbonation, and oxidation) and crystallization of high-temperature minerals, occurred simultaneously, leading to significant changes in observed pore/grain structures. Pore structures in the protoliths, and in lowand high-grade metamorphic rocks show surface (Ds) and mass (Dm) pore fractal geometries with gradual increases in both Ds and Dm values as a function of metamorphic grade. This suggests that increases in pore volume and formation of less branching pore networks are accompanied by a roughening of pore/grain interfaces. Additionally, pore evolution during combustion metamorphism is also characterized by reduced contributions from small-scale pores to the cumulative porosity in the high-grade rocks. At high temperatures, small-scale pores may be preferentially closed by the formation of high-temperature minerals, producing a rougher morphology with increasing temperature. Alternatively, large-scale pores may develop at the expense of small-scale pores. These observations (pore fractal geometry and cumulative porosity) indicate that the evolution of pore/grain structures is correlated with the growth of high-temperature phases and is a consequence of the energy balance between pore/grain surface energy and energy arising from heterogeneous phase contacts. The apparent pore volume density further suggests that the localized time/temperature development of the high-grade Hatrurim rocks is not simply an extension of that of the low-grade rocks. The former likely represents the "hot spots (burning foci)" in the overall metamorphic terrain while the latter may represent contact aureoles.

  10. Deuterium Labeling Together with Contrast Variation Small-angle Neutron Scattering Suggests How Skp Captures and Releases Unfolded Outer Membrane Proteins

    PubMed Central

    Zaccai, Nathan R.; Sandlin, Clifford W.; Hoopes, James T.; Curtis, Joseph E.; Fleming, Patrick J.; Fleming, Karen G.; Krueger, Susan

    2016-01-01

    In gram-negative bacteria, the chaperone protein Skp forms specific and stable complexes with membrane proteins while they are transported across the periplasm to the outer membrane. The jellyfish-like architecture of Skp is similar to the eukaryotic and archeal prefoldins and the mitochondrial Tim chaperones, that is α-helical ‘tentacles’ extend from a β-strand ‘body’ to create an internal cavity. Contrast variation small-angle neutron scattering (SANS) experiments on Skp alone in solution and bound in two different complexes to unfolded outer membrane proteins (uOMPs), OmpA and OmpW, demonstrate that the helical tentacles of Skp bind their substrate in a clamp-like mechanism in a conformation similar to that previously observed in the apo crystal structure of Skp. Deuteration of the uOMP component combined with contrast variation analysis allowed the shapes of Skp and uOMP as well as the location of uOMP with respect to Skp to be determined in both complexes. This represents unique information that could not be obtained without deuterium labeling of the uOMPs. The data yield the first direct structural evidence that the α-helical Skp tentacles move closer together on binding its substrate and that the structure of Skp is different when binding different uOMPs. This work presents, by example, a tutorial on performing SANS experiments using both deuterium labeling and contrast variation, including SANS theory, sample preparation, data collection, sample quality validation, data analysis and structure modeling. PMID:26791979

  11. Small-angle neutron scattering study of differences in phase behavior of silica nanoparticles in the presence of lysozyme and bovine serum albumin proteins

    NASA Astrophysics Data System (ADS)

    Yadav, Indresh; Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2014-03-01

    The differences in phase behavior of anionic silica nanoparticles (88 Å) in the presence of two globular proteins [cationic lysozyme (molecular weight (MW) 14.7 kD) and anionic bovine serum albumin (BSA) (MW 66.4 kD)] have been studied by small-angle neutron scattering. The measurements were carried out on a fixed concentration (1 wt %) of Ludox silica nanoparticles with varying concentrations of proteins (0-5 wt %) at pH = 7. It is found that, despite having different natures (opposite charges), both proteins can render to the same kind of aggregation of silica nanoparticles. However, the concentration regions over which the aggregation is observed are widely different for the two proteins. Lysozyme with very small amounts (e.g., 0.01 wt %) leads to the aggregation of silica nanoparticles. On the other hand, silica nanoparticles coexist with BSA as independent entities at low protein concentrations and turn to aggregates at high protein concentrations (>1 wt %). In the case of lysozyme, the charge neutralization by the protein on the nanoparticles gives rise to the protein-mediated aggregation of the nanoparticles. The nanoparticle aggregates coexist with unaggregated nanoparticles at low protein concentrations, whereas, they coexist with a free protein at higher protein concentrations. For BSA, the nonadsorbing nature of the protein produces the depletion force that causes the aggregation of the nanoparticles at higher protein concentrations. The evolution of the interaction is modeled by the two Yukawa potential, taking account of both attractive and repulsive terms of the interaction in these systems. The nanoparticle aggregation is found to be governed by the short-range attraction for lysozyme and the long-range attraction for BSA. The aggregates are characterized by the diffusion limited aggregate type of mass fractal morphology.

  12. Effect of Protein Incorporation on the Nanostructure of the Bicontinuous Microemulsion Phase of Winsor-III Systems: A Small-Angle Neutron Scattering Study

    SciTech Connect

    Hayes, Douglas G.; Gomez del Rio, Javier A.; Ye, Ran; Urban, Volker S.; Pingali, Sai Venkatesh; O’Neill, Hugh M.

    2015-01-20

    Small-angle neutron scattering (SANS) analysis using the Teubner₋Strey model has been employed to evaluate the effect of protein incorporation into the middle, bicontinuous microemulsion (BμE) phase of Winsor-III (WIII) systems formed by an aerosol-OT (AOT)/alkyl ethoxylate mixed surfactant system to understand better the extraction of proteins into and out of BμEs and to study the effect of proteins on a system that serves as a biomimetic analog of cell membranes. Under conditions of high salinity, the incorporation of positively charged proteins cytochrome c, lysozyme, and α-chymotrypsin, near their solubilization limit in the BμEs promoted the release of water and oil from the BμEs, a decrease in the quasi-periodic repeat distance (d), an increase in ordering (a decrease in the amphiphilicity factor, fa) for the surfactant monolayers, and a decrease in the surface area per surfactant headgroup, suggesting that the proteins affected the self-assembly of components in the BμE phase and produced Debye shielding of AOTs sulfonate headgroup. For WIII systems possessing lower salinity, cytochrome c reduced the efficiency of surfactant in the BμE phase, noted by increases in d and fa, suggesting that the enzyme and AOT underwent ion pairing. We find that the results of this study demonstrate the importance of ionic strength to modulate proteinsurfactant interactions, which in turn will control the release of proteins encapsulated in the BμEs, relevant to WIII-based protein extraction and controlled release from BμE delivery systems, and demonstrate the utility of BμEs as a model system to understand the effect of proteins on biomembranes.

  13. Simultaneous small-angle neutron scattering and Fourier transform infrared spectroscopic measurements on cocrystals of syndiotactic polystyrene with polyethylene glycol dimethyl ethers1

    PubMed Central

    Kaneko, Fumitoshi; Seto, Naoki; Sato, Shuma; Radulescu, Aurel; Schiavone, Maria Maddalena; Allgaier, Jürgen; Ute, Koichi

    2016-01-01

    Syndiotactic polystyrene (sPS) is a crystalline polymer which has a unique property; it is able to form cocrystals with a wide range of chemical compounds, in which the guest molecules are confined in the vacancies of the host sPS crystalline region. Recently, it has been found that even polyethylene glycol oligomers with a molecular weight of more than several hundreds can be introduced into the sPS crystalline region. It is quite important to know how such a long-chain molecule is stored in the host sPS lattice. To tackle this issue, a new simultaneous measurement method combing small-angle neutron scattering and Fourier transform infrared spectroscopy (SANS/FTIR), which has been recently developed by the authors, was applied to an sPS cocrystal with polyethylene glycol dimethyl ether with a molecular weight of 500 (PEGDME500). The temperature-dependent changes of the SANS profile and FTIR spectrum were followed from room temperature up to 413 K for a one-dimensionally oriented SANS/PEGDME500 cocrystal sample. The intensity of the reflections due to the stacking of crystalline lamellae showed a significant temperature dependence. The two-dimensional pattern in the high Q region of SANS also changed depending on temperature. The combined information obtained by SANS and FTIR suggested that PEGDME500 molecules are distributed in both the crystalline and amorphous regions in the low-temperature region close to room temperature, but they are predominantly included in the amorphous region in the high-temperature region. It was also suggested by the two-dimensional SANS profile that PEGDME500 molecules in the crystalline region have an elongated structure along the thickness direction of the crystalline lamellae. PMID:27738412

  14. Simultaneous small-angle neutron scattering and Fourier transform infrared spectroscopic measurements on cocrystals of syndiotactic polystyrene with polyethylene glycol dimethyl ethers.

    PubMed

    Kaneko, Fumitoshi; Seto, Naoki; Sato, Shuma; Radulescu, Aurel; Schiavone, Maria Maddalena; Allgaier, Jürgen; Ute, Koichi

    2016-10-01

    Syndiotactic polystyrene (sPS) is a crystalline polymer which has a unique property; it is able to form cocrystals with a wide range of chemical compounds, in which the guest molecules are confined in the vacancies of the host sPS crystalline region. Recently, it has been found that even polyethylene glycol oligomers with a molecular weight of more than several hundreds can be introduced into the sPS crystalline region. It is quite important to know how such a long-chain molecule is stored in the host sPS lattice. To tackle this issue, a new simultaneous measurement method combing small-angle neutron scattering and Fourier transform infrared spectroscopy (SANS/FTIR), which has been recently developed by the authors, was applied to an sPS cocrystal with polyethylene glycol dimethyl ether with a molecular weight of 500 (PEGDME500). The temperature-dependent changes of the SANS profile and FTIR spectrum were followed from room temperature up to 413 K for a one-dimensionally oriented SANS/PEGDME500 cocrystal sample. The intensity of the reflections due to the stacking of crystalline lamellae showed a significant temperature dependence. The two-dimensional pattern in the high Q region of SANS also changed depending on temperature. The combined information obtained by SANS and FTIR suggested that PEGDME500 molecules are distributed in both the crystalline and amorphous regions in the low-temperature region close to room temperature, but they are predominantly included in the amorphous region in the high-temperature region. It was also suggested by the two-dimensional SANS profile that PEGDME500 molecules in the crystalline region have an elongated structure along the thickness direction of the crystalline lamellae.

  15. Small Angle Neutron Scattering Study of Conformation of Oligo(ethylene glycol) Grafted Polystyrene in Dilute Solutions: Effect of the Backbone Length

    SciTech Connect

    Cheng, Gang; Hong, Kunlun; Hua, Fengjun; Melnichenko, Yuri B; Wignall, George D; Mays, Jimmy

    2008-01-01

    The conformation and clusterization of comb like polymers of polystyrene densely grafted with oligo(ethylene glycol) (OEG) side chains in 1.0 wt% solutions of D2O, toluene-d8 and methanol-d4 was investigated as a function of the degree of polymerization (DP) of the backbone by small angle neutron scattering (SANS). Each side chain had four EG repeat units and the DP of the polystyrene backbone was varied from 8 to 85. The global conformation of the polymers in toluene and methanol was shown to assume ellipsoidal, cylindrical or worm-like chain morphologies with increasing DP of the polystyrene backbone. At the same time, in D2O, the polymer conformation was described by the form factor of rigid cylinders. The second viral coefficient was measured for the polymer with a DP of 85 in all three solvents and the solvent quality of toluene, methanol and D2O was identified as good, marginal and poor for this polymer. Due to a poor solvent quality, the PS backbone (DP = 85) is partially collapsed in D2O whereas it is moderately expanded in toluene and methanol. Polymers with the DP of 8 were found to aggregate into clusters in all three solvents, with the characteristic size between 100 and 200 ?and a fractal dimension of 2. With increase of the DP, the clusters diminished in D2O and completely disappeared in toluene and methanol. This observation suggests that the clusterization of these short side-chain polymers is caused by end group and hydrogen bonding interactions between different chains.

  16. A combined method of small-angle neutron scattering and neutron radiography to visualize water in an operating fuel cell over a wide length scale from nano to millimeter

    NASA Astrophysics Data System (ADS)

    Iwase, H.; Koizumi, S.; Iikura, H.; Matsubayashi, M.; Yamaguchi, D.; Maekawa, Y.; Hashimoto, T.

    2009-06-01

    In order to visualize water generated in an operating polymer electrolyte fuel cell (PEFC), a neutron radiography (NR) apparatus, composed of a scintillator, optical mirrors and a CCD camera, was installed at a sample position of the focusing and polarized neutron small-angle scattering (SANS) spectrometer (SANS-J-II) at research reactor JRR-3 at Japan Atomic Energy Agency, Tokai, Japan. By combining SANS and NR, we aim to cover a wide length scale from nanometer to millimeter. The new method succeeded in detecting a spatial distribution of the water generated in individual cell elements; NR detected the water in a gas diffusion layer and a flow field, whereas SANS quantitatively determines the water content in a membrane electrode assembly (MEA).

  17. Small-angle neutron scattering instrument of Institute for Solid State Physics, the Univeristy of Tokyo (SANS-U) and its application to biology

    SciTech Connect

    Ito, Yuji; Imai, Masayuki; Takahashi, Shiro

    1994-12-31

    A small-angle neutron spectrometer (SANS-U) suitable for the study of mesoscopic structure in the field of polymer chemistry and biology, has been constructed at the guide hall of JRR-3M reactor at the Japan Atomic Energy Research Institute. The instrument is 32m long and utilizes a mechanical velocity selector and pinhole collimation to provide a continuous beam with variable wavelength in the range from 5 to 10{Angstrom}. The neutron detector is a 65 x 65cm{sup 2} 2D position sensitive proportional counter. The practical Q range of SANS-U is 0.0008 to 0.45{Angstrom}{sup -1}. The design, characteristics and performance of SANS-U are described with some biological studies using SANS-U.

  18. Small-angle X-ray and neutron scattering study of Nafion-SiO2 hybrid membranes prepared in different solvent media

    NASA Astrophysics Data System (ADS)

    Dresch, M. A.; Matos, B. R.; Fonseca, F. C.; Santiago, E. I.; Carmo, M.; Lanfredi, A. J. C.; Balog, S.

    2015-01-01

    Nafion-SiO2 hybrid electrolytes were synthesized by sol-gel reaction. The homogeneity, structural properties, and proton conductivity of the hybrid membranes were studied. Small-angle scattering analyses indicate that the Nafion structural matrix was preserved on the nanoscale, and the growth of silica particles occurred both in the ionic and nonionic domains of Nafion, which resulted in hybrids with characteristic morphologies. The water uptake and the weight fraction of the inorganic phase were found to be dependent on the alcohol solvent used for the sol-gel synthesis. Nafion-silica hybrids with homogeneous distribution of the inorganic phase were obtained using methanol as the solvent for the sol-gel reaction. The observed microstructural properties of the Nafion-silica membranes were related to enhanced proton conductivity at high temperatures and low relative humidity conditions.

  19. Small-angle scattering model for multilamellar vesicles

    SciTech Connect

    Frielinghaus, Henrich

    2007-11-15

    A small-angle neutron-x-ray-light-scattering model for multilamellar vesicles is developed on the basis of a simple geometry. N spherical shells with radii of an arithmetic series are allowed for displacements {delta}R which are limited by {delta}Rscattering angles. Then the important bilayer spacing is larger. The predictive power of the model lies in the connection of the compactness with N and in the maximum correlation peak sharpness. This model considers many length scales at a time while existing theories focus on length scales of the bilayer spacing and the bilayer itself.

  20. Branch Content in Hybrid Materials using Small-Angle Scattering

    NASA Astrophysics Data System (ADS)

    Beaucage, Greg

    2005-03-01

    Inorganic/organic hybrid materials often display ramified mass- fractal structures characterized by primary particle size, aggregate size, and mass-fractal dimension. Physical properties, such as mechanical and dynamic mechanical properties and electrical conductivity (in carbon composites for instance), can not be predicted using only these structural features since such properties are intimately tied to the degree and type of branching as shown by Witten [1]. Witten suggested the use of the minimum dimension, or the related connectivity dimension, to calculate mechanical response in these hybrid systems. A viable technique to quantify the minimum dimension and connectivity dimension in hybrid materials has, until recently, been absent from the literature. This presentation will discuss the use of small-angle x-ray and neutron scattering to describe branch content in hybrid materials [2] and will outline an approach to use the minimum dimension and connectivity dimension to predict static and dynamic mechanical properties for hybrid materials based on structure [1, 3]. 1. Witten TA, Rubinstein M, Colby RH Reinforcement of Rubber by Fractal Aggregates J Phys II 3 (3): 367-383 (1993). 2. Beaucage G Determination of branch fraction and minimum dimension of mass-fractal aggregates Phys Rev E 70 (3): art. no. 031401 Part 1 (2004). 3. Kohls DJ, Beaucage G Rational design of reinforced rubber Curr Opin Solid St M 6 (3): 183-194 (2002).

  1. Reconstruction from small-angle neutron scattering measurements of the real space magnetic field distribution in the mixed state of Sr2RuO4.

    PubMed

    Kealey, P G; Riseman, T M; Forgan, E M; Galvin, L M; Mackenzie, A P; Lee, S L; Paul, D M; Cubitt, R; Agterberg, D F; Heeb, R; Mao, Z Q; Maeno, Y

    2000-06-26

    We have measured the diffracted neutron scattering intensities from the square magnetic flux lattice in the perovskite superconductor Sr2RuO4, which is thought to exhibit p-wave pairing with a two-component order parameter. The relative intensities of different flux lattice Bragg reflections over a wide range of field and temperature have been shown to be inconsistent with a single component Ginzburg-Landau theory but qualitatively agree with a two-component p-wave Ginzburg-Landau theory.

  2. Evaluation of Pore Networks in Caprocks at Geologic Storage Sites: A Combined Study using High Temperature and Pressure Reaction Experiments, Small Angle Neutron Scattering, and Focused Ion Beam-Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Mouzakis, K. M.; Sitchler, A.; Wang, X.; McCray, J. E.; Kaszuba, J. P.; Rother, G.; Dewers, T. A.; Heath, J. E.

    2011-12-01

    Low permeability rock units, often shales or mudstones, that overlie geologic formations under consideration for CO2 sequestration will help contain injected CO2. CO2 that does flow through these rocks will dissolve into the porewaters, creating carbonic acid lowering the pH. This perturbation of the system may result in mineral dissolution or precipitation, which can change the pore structure and impact the flow properties of the caprocks. In order to investigate the impacts that reaction can have on caprock pore structure, we performed a combination of high pressure high temperature reaction experiments, small angle neutron scattering (SANS) experiments and high resolution focused ion beam-scanning electron microscope (FIB-SEM) imaging on samples from the Gothic shale and Marine Tuscaloosa Group. Small angle neutron scattering was performed on unreacted and reacted caprocks at the High Flux Isotope Reactor at Oak Ridge National Laboratory. New precipitates and pores are observed in high-resolution images of the reacted samples. The precipitates have been preliminarily identified as gypsum or anhydrite, and sulfide minerals. Results from small angle neutron scattering, a technique that provides information about pores and pore/mineral interfaces at scales ~ 5 to 300 nm, show an increased porosity and specific surface area after reaction with brine and CO2. However, there appear to be differences in how the pore networks change between the two samples that are related to sample mineralogy and original pore network structure. Changes to pores and formation of new pores may lead to different capillary sealing behavior and permeability. This combination of controlled laboratory experiments, neutron scattering and high-resolution imaging provides detailed information about the geochemical processes that occur at the pore scale as CO2 reacts with rocks underground. Such information is integral to the evaluation of large-scale CO2 sequestration as a feasible technology

  3. Small-angle scattering gives direct structural information about a membrane protein inside a lipid environment.

    PubMed

    Kynde, Søren A R; Skar-Gislinge, Nicholas; Pedersen, Martin Cramer; Midtgaard, Søren Roi; Simonsen, Jens Baek; Schweins, Ralf; Mortensen, Kell; Arleth, Lise

    2014-02-01

    Monomeric bacteriorhodopsin (bR) reconstituted into POPC/POPG-containing nanodiscs was investigated by combined small-angle neutron and X-ray scattering. A novel hybrid approach to small-angle scattering data analysis was developed. In combination, these provided direct structural insight into membrane-protein localization in the nanodisc and into the protein-lipid interactions. It was found that bR is laterally decentred in the plane of the disc and is slightly tilted in the phospholipid bilayer. The thickness of the bilayer is reduced in response to the incorporation of bR. The observed tilt of bR is in good accordance with previously performed theoretical predictions and computer simulations based on the bR crystal structure. The result is a significant and essential step on the way to developing a general small-angle scattering-based method for determining the low-resolution structures of membrane proteins in physiologically relevant environments.

  4. Observation of Well-ordered Metastable Vortex Lattice Phases in Superconducting MgB2 Using Small-Angle Neutron Scattering

    SciTech Connect

    Das, Pinaki; Rastovski, Catherine; O'Brien, Timothy; Schlesinger, Kimberly; Dewhurst, Charles; Debeer-Schmitt, Lisa M; Zhigadlo, Nikolai; Karpinski, Janusz; Eskildsen, Morten

    2012-01-01

    The vortex lattice (VL) symmetry and orientation in clean type-II superconductors depends sensitively on the host material anisotropy, vortex density and temperature, frequently leading to rich phase diagrams. Typically, a well-ordered VL is taken to imply a ground-state configuration for the vortex-vortex interaction. Using neutron scattering we studied the VL in MgB2 for a number of field-temperature histories, discovering an unprecedented degree of metastability in connection with a known, second-order rotation transition. This allows, for the first time, structural studies of a well-ordered, nonequilibrium VL. While the mechanism responsible for the longevity of the metastable states is not resolved, we speculate it is due to a jamming of VL domains, preventing a rotation to the ground-state orientation.

  5. Windows for small-angle X-ray scattering cryostats.

    PubMed

    Lurio, Laurence; Mulders, Norbert; Paetkau, Mark; Jemian, Pete R; Narayanan, Suresh; Sandy, Alec

    2007-11-01

    To determine the suitability of commonly used windows for small-angle X-ray scattering, a range of materials, including Kapton, (aluminized) Mylar, beryllium, high-purity aluminium foil, mica and silicon nitride have been studied. At small wavevector transfers, Q, in the range 2 x 10(-3) to 0.2 nm(-1), the scattering from Kapton, mica and beryllium is reasonably well described by power laws in Q with exponents of -3.25, -3.6 and -3.9, respectively. There are large variations in the scattering from mica, but a freshly cleaved natural mica window was by far the weakest scatterer. For applications where radiation in the infrared or visible range should be blocked, aluminized Mylar is the most suitable material. Both Mylar and Kapton can be used to make very simple demountable superfluid-tight windows using indium O-ring seals.

  6. A small angle neutron scattering study of the adsorbed asphaltene layer in water-in-hydrocarbon emulsions: structural description related to stability.

    PubMed

    Jestin, Jacques; Simon, Sébastien; Zupancic, Lina; Barré, Loïc

    2007-10-09

    We have developed a specific protocol to study with SANS measurements, the structure of the interfacial film layer in water-in-oil emulsions stabilized by asphaltene. Using the contrast matching technique available for neutron scattering, we have access to both the composition and the quantity of interface. The results obtained give us a view of the asphaltene aggregates in the interfacial film, which are structured as a monolayer and show a direct correlation between the size of asphaltene aggregates in solution and the thickness of the film layer. The organization of the interface has been studied as a function of several parameters such as the quantity of resins, i.e., the size of aggregates, the pH of the aqueous phase, and the aging time of the emulsions and the consequences of these variations on the macroscopic stability of these emulsions. We show that the key parameter for the stability is the inter-asphaltene aggregate interaction inside the film layer. Changing the attractive/repulsive balance between the aggregates in the film at the microscopic scale, by changing the aggregate's size or the aggregate's ionization, has a direct incidence on the quantity of water recovered after centrifugation: the stronger the attraction between aggregates in the film, the more stable the emulsion is.

  7. Solution structure and excitation energy transfer in phycobiliproteins of Acaryochloris marina investigated by small angle scattering.

    PubMed

    Golub, M; Combet, S; Wieland, D C F; Soloviov, D; Kuklin, A; Lokstein, H; Schmitt, F-J; Olliges, R; Hecht, M; Eckert, H-J; Pieper, J

    2017-04-01

    The structure of phycobiliproteins of the cyanobacterium Acaryochloris marina was investigated in buffer solution at physiological temperatures, i.e. under the same conditions applied in spectroscopic experiments, using small angle neutron scattering. The scattering data of intact phycobiliproteins in buffer solution containing phosphate can be well described using a cylindrical shape with a length of about 225Å and a diameter of approximately 100Å. This finding is qualitatively consistent with earlier electron microscopy studies reporting a rod-like shape of the phycobiliproteins with a length of about 250 (M. Chen et al., FEBS Letters 583, 2009, 2535) or 300Å (J. Marquart et al., FEBS Letters 410, 1997, 428). In contrast, phycobiliproteins dissolved in buffer lacking phosphate revealed a splitting of the rods into cylindrical subunits with a height of 28Å only, but also a pronounced sample aggregation. Complementary small angle neutron and X-ray scattering experiments on phycocyanin suggest that the cylindrical subunits may represent either trimeric phycocyanin or trimeric allophycocyanin. Our findings are in agreement with the assumption that a phycobiliprotein rod with a total height of about 225Å can accommodate seven trimeric phycocyanin subunits and one trimeric allophycocyanin subunit, each of which having a height of about 28Å. The structural information obtained by small angle neutron and X-ray scattering can be used to interpret variations in the low-energy region of the 4.5K absorption spectra of phycobiliproteins dissolved in buffer solutions containing and lacking phosphate, respectively.

  8. Accounting for thermodynamic non-ideality in the Guinier region of small-angle scattering data of proteins.

    PubMed

    Scott, David J

    2016-12-01

    Hydrodynamic studies of the solution properties of proteins and other biological macromolecules are often hard to interpret when the sample is present at a reasonably concentrated solution. The reason for this is that solutions exhibit deviations from ideal behaviour which is manifested as thermodynamic non-ideality. The range of concentrations at which this behaviour typically is exhibited is as low as 1-2 mg/ml, well within the range of concentrations used for their analysis by techniques such as small-angle scattering. Here we discuss thermodynamic non-ideality used previously used in the context of light scattering and sedimentation equilibrium analytical ultracentrifugation and apply it to the Guinier region of small-angle scattering data. The results show that there is a complementarity between the radially averaged structure factor derived from small-angle X-ray scattering/small-angle neutron scattering studies and the second virial coefficient derived from sedimentation equilibrium analytical ultracentrifugation experiments.

  9. The roles of RIIbeta linker and N-terminal cyclic nucleotide-binding domain in determining the unique structures of Type IIbeta Protein Kinase A. A small angle X-ray and neutron scattering study

    DOE PAGES

    Blumenthal, Donald K.; Copps, Jeffrey; Smith-Nguyen, Eric V.; ...

    2014-08-11

    Protein kinase A (PKA) is ubiquitously expressed and is responsible for regulating many important cellular functions in response to changes in intracellular cAMP concentrations. Moreover, the PKA holoenzyme is a tetramer (R2:C2), with a regulatory subunit homodimer (R2) that binds and inhibits two catalytic (C) subunits; binding of cAMP to the regulatory subunit homodimer causes activation of the catalytic subunits. Four different R subunit isoforms exist in mammalian cells, and these confer different structural features, subcellular localization, and biochemical properties upon the PKA holoenzymes they form. The holoenzyme containing RIIβ is structurally unique in that the type IIβ holoenzyme ismore » much more compact than the free RIIβ homodimer. We have used small angle x-ray scattering and small angle neutron scattering to study the solution structure and subunit organization of a holoenzyme containing an RIIβ C-terminal deletion mutant (RIIβ(1–280)), which is missing the C-terminal cAMP-binding domain to better understand the structural organization of the type IIβ holoenzyme and the RIIβ domains that contribute to stabilizing the holoenzyme conformation. These results demonstrate that compaction of the type IIβ holoenzyme does not require the C-terminal cAMP-binding domain but rather involves large structural rearrangements within the linker and N-terminal cyclic nucleotide-binding domain of the RIIβ homodimer. The structural rearrangements are significantly greater than seen previously with RIIα and are likely to be important in mediating short range and long range interdomain and intersubunit interactions that uniquely regulate the activity of the type IIβ isoform of PKA.« less

  10. The roles of RIIbeta linker and N-terminal cyclic nucleotide-binding domain in determining the unique structures of Type IIbeta Protein Kinase A. A small angle X-ray and neutron scattering study

    SciTech Connect

    Blumenthal, Donald K.; Copps, Jeffrey; Smith-Nguyen, Eric V.; Zhang, Ping; Heller, William T.; Taylor, Susan S.

    2014-08-11

    Protein kinase A (PKA) is ubiquitously expressed and is responsible for regulating many important cellular functions in response to changes in intracellular cAMP concentrations. Moreover, the PKA holoenzyme is a tetramer (R2:C2), with a regulatory subunit homodimer (R2) that binds and inhibits two catalytic (C) subunits; binding of cAMP to the regulatory subunit homodimer causes activation of the catalytic subunits. Four different R subunit isoforms exist in mammalian cells, and these confer different structural features, subcellular localization, and biochemical properties upon the PKA holoenzymes they form. The holoenzyme containing RIIβ is structurally unique in that the type IIβ holoenzyme is much more compact than the free RIIβ homodimer. We have used small angle x-ray scattering and small angle neutron scattering to study the solution structure and subunit organization of a holoenzyme containing an RIIβ C-terminal deletion mutant (RIIβ(1–280)), which is missing the C-terminal cAMP-binding domain to better understand the structural organization of the type IIβ holoenzyme and the RIIβ domains that contribute to stabilizing the holoenzyme conformation. These results demonstrate that compaction of the type IIβ holoenzyme does not require the C-terminal cAMP-binding domain but rather involves large structural rearrangements within the linker and N-terminal cyclic nucleotide-binding domain of the RIIβ homodimer. The structural rearrangements are significantly greater than seen previously with RIIα and are likely to be important in mediating short range and long range interdomain and intersubunit interactions that uniquely regulate the activity of the type IIβ isoform of PKA.

  11. The roles of the RIIβ linker and N-terminal cyclic nucleotide-binding domain in determining the unique structures of the type IIβ protein kinase A: a small angle x-ray and neutron scattering study.

    PubMed

    Blumenthal, Donald K; Copps, Jeffrey; Smith-Nguyen, Eric V; Zhang, Ping; Heller, William T; Taylor, Susan S

    2014-10-10

    Protein kinase A (PKA) is ubiquitously expressed and is responsible for regulating many important cellular functions in response to changes in intracellular cAMP concentrations. The PKA holoenzyme is a tetramer (R2:C2), with a regulatory subunit homodimer (R2) that binds and inhibits two catalytic (C) subunits; binding of cAMP to the regulatory subunit homodimer causes activation of the catalytic subunits. Four different R subunit isoforms exist in mammalian cells, and these confer different structural features, subcellular localization, and biochemical properties upon the PKA holoenzymes they form. The holoenzyme containing RIIβ is structurally unique in that the type IIβ holoenzyme is much more compact than the free RIIβ homodimer. We have used small angle x-ray scattering and small angle neutron scattering to study the solution structure and subunit organization of a holoenzyme containing an RIIβ C-terminal deletion mutant (RIIβ(1-280)), which is missing the C-terminal cAMP-binding domain to better understand the structural organization of the type IIβ holoenzyme and the RIIβ domains that contribute to stabilizing the holoenzyme conformation. Our results demonstrate that compaction of the type IIβ holoenzyme does not require the C-terminal cAMP-binding domain but rather involves large structural rearrangements within the linker and N-terminal cyclic nucleotide-binding domain of the RIIβ homodimer. The structural rearrangements are significantly greater than seen previously with RIIα and are likely to be important in mediating short range and long range interdomain and intersubunit interactions that uniquely regulate the activity of the type IIβ isoform of PKA.

  12. Small-angle electron scattering from magnetic artificial lattice.

    PubMed

    Takayanagi, Kazuya; Koyama, Tsukasa; Mori, Shigeo; Harada, Ken; Togawa, Yoshihiko

    2012-01-01

    In this study, quantitative reciprocal-space analyses of magnetic domain structures in magnetic artificial lattices of patterned elements were performed by means of the small-angle electron scattering (SAES) technique. Using a conventional transmission electron microscope with a LaB(6) thermal-emission electron gun, Lorentz deflection due to magnetic moments in patterned elements and Bragg diffraction due to the lattice periodicity are simultaneously recorded at an angle of the order of less than 1 10(-)(6) rad when using electron waves with high spatial coherency and large camera length. The present SAES technique together with TEM real-space imaging methods such as Lorentz microscopy will be useful in analyzing electromagnetic fields in nano-scaled materials.

  13. Small-angle electron scattering of magnetic fine structures.

    PubMed

    Togawa, Yoshihiko

    2013-06-01

    Magnetic structures in magnetic artificial lattices and chiral magnetic orders in chiral magnets have been quantitatively analyzed in the reciprocal space by means of small-angle electron scattering (SAES) method. Lorentz deflection due to magnetic moments and Bragg diffraction due to periodicity are simultaneously recorded at an angle of the order of or less than 1 × 10(-6) rad, using a camera length of more than 100 m. The present SAES method, together with TEM real-space imaging methods such as in-situ Lorentz microscopy, is very powerful in analyzing magnetic fine structures in magnetic materials. Indeed, the existence of both a chiral helimagnetic structure and a chiral magnetic soliton lattice in a chiral magnet CrNb3S6 has been successfully verified for the first time using the present complementary methods.

  14. Small Angle Elastic Scattering of Protons off of Spinless Nuclei.

    NASA Astrophysics Data System (ADS)

    Ling, Alan Graham

    1988-12-01

    Elastic differential cross sections and analyzing powers for 800 MeV protons incident on ^ {12}C, ^{40} Ca, and ^{208}Pb in the momentum transfer range 20 MeV/c < q < 130 MeV/c have been measured. The data was taken with the High Resolution Spectrometer (HRS) at the Los Alamos Meson Physics Facility. Special delay -line drift chambers with dead regions for the beam to pass through them were used to obtain the data. Through the interference of the Coulomb and nuclear contributions to the differential cross section in the small angle region, the ratio of the real to imaginary part of the forward nuclear amplitude alpha_{rm n}(0) = Ref_{rm n}(0)/Imf_{rm n }(0) is extracted. The importance of knowing this quantity at lower energies in order to study the differences between relativistic and non-relativistic scattering theories is discussed.

  15. Disordered porous solids : from chord distributions to small angle scattering

    NASA Astrophysics Data System (ADS)

    Levitz, P.; Tchoubar, D.

    1992-06-01

    Disordered biphasic porous solids are examples of complex interfacial media. Small angle scattering strongly depends on the geometrical properties of the internal surface partitioning a porous system. Properties of the second derivative of the bulk autocorrelation function quantitatively defines the level of connection between the small angle scattering and the statistical properties of this interface. A tractable expression of this second derivative, involving the pore and the mass chord distribution functions, was proposed by Mering and Tchoubar (MT). Based on the present possibility to make a quantitative connection between imaging techniques and the small angle scattering, this paper tries to complete and to extend the MT approach. We first discuss how chord distribution functions can be used as fingerprints of the structural disorder. An explicit relation between the small angle scattering and these chord distributions is then proposed. In a third part, the application to different types of disorder is critically discussed and predictions are compared to available experimental data. Using image processing, we will consider three types of disorder : the long-range Debye randomness, the “ correlated " disorder with a special emphasis on the structure of a porous glass (the vycor), and, finally, complex structures where length scale invariance properties can be observed. Les solides poreux biphasiques sont des exemples de milieux interfaciaux complexes. La diffusion aux petits angles (SAS) dépend fortement des propriétés géométriques de l'interface partitionant le milieu poreux. Les propriétés de la dérivée seconde de la fonction d'autocorrélation de densité définit quantitativement le niveau de connection entre la diffusion aux petits angles et les caractéristiques statistiques de cette interface. Une expression utilisable de cette seconde dérivée, impliquant les distributions de cordes associées à la phase massique et au réseau de pores, fut

  16. Small angle scattering methods to study porous materials under high uniaxial strain

    NASA Astrophysics Data System (ADS)

    Le Floch, Sylvie; Balima, Félix; Pischedda, Vittoria; Legrand, Franck; San-Miguel, Alfonso

    2015-02-01

    We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.

  17. Small angle scattering methods to study porous materials under high uniaxial strain

    SciTech Connect

    Le Floch, Sylvie Balima, Félix; Pischedda, Vittoria; Legrand, Franck; San-Miguel, Alfonso

    2015-02-15

    We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.

  18. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering.

    PubMed

    Allen, Andrew J; Zhang, Fan; Kline, R Joseph; Guthrie, William F; Ilavsky, Jan

    2017-04-01

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008-0.25 Å(-1), together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments that employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. The validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.

  19. Small angle x-ray scattering with edge-illumination

    NASA Astrophysics Data System (ADS)

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-08-01

    Sensitivity to sub-pixel sample features has been demonstrated as a valuable capability of phase contrast x-ray imaging. Here, we report on a method to obtain angular-resolved small angle x-ray scattering distributions with edge-illumination- based imaging utilizing incoherent illumination from an x-ray tube. Our approach provides both the three established image modalities (absorption, differential phase and scatter strength), plus a number of additional contrasts related to unresolved sample features. The complementarity of these contrasts is experimentally validated by using different materials in powder form. As a significant application example we show that the extended complementary contrasts could allow the diagnosis of pulmonary emphysema in a murine model. In support of this, we demonstrate that the properties of the retrieved scattering distributions are consistent with the expectation of increased feature sizes related to pulmonary emphysema. Combined with the simplicity of implementation of edge-illumination, these findings suggest a high potential for exploiting extended sub-pixel contrasts in the diagnosis of lung diseases and beyond.

  20. Microstructure and rheology of a thermoreversible gel under large amplitude oscillatory shear (LAOS) deformation using time-resolved oscillatory rheo-small-angle neutron scattering (tOr-SANS)

    NASA Astrophysics Data System (ADS)

    Kim, Jung Min; Gurnon, A. Kate; Wagner, Norman; Eberle, Aaron

    2013-03-01

    Large amplitude oscillatory shear (LAOS) rheology is an effective way of studying the nonlinear dynamics of complex fluids. Here, we present a new method for a direct, quantitative study of the microstructure under LAOS deformation in the framework of the alignment factor, Af. We use a model thermoreversible adhesive hard-sphere system composed of octadecyl-coated silica particles suspended in n-tetradecane. With temperature the particle potential is controlled and the system is shifted from behaving as a near hard-sphere to an adhesive hard-sphere system leading to aggregation and ultimately a dynamical arrest transition to macroscopic gelation. Time-resolved oscillatory rheo-small-angle neutron scattering (tOr-SANS) measurements in the 1-3 plane are performed by stroboscopically probing the structural evolution as a function of time during LAOS. Under strong shear, the 2D scattering pattern of the system in the gelled state exhibits a strong anisotropy commonly known as a ``butterfly'' pattern, which corresponds to the stretching of the microstructure along the flow direction. The first structure-Lissajous plots of this model system are presented in terms of an order parameter and Af as a function of instantaneous strain and strain rate. This new analysis demonstrates a novel method for simultaneously measuring the rheology and microstructure during a time-dependent deformation (LAOS).

  1. Small angle elastic scattering of protons off of spinless nuclei

    SciTech Connect

    Ling, A.G.

    1988-07-01

    Elastic differential cross sections and analyzing powers for 800 MeV protons incident on /sup 12/C, /sup 40/Ca, and /sup 208/Pb in the momentum transfer range 20 MeV/c < q < 130 MeV/c have been measured. The data was taken with the High Resolution Spectrometer (HRS) at the Los Alamos Meson Physics Facility. Special delay-line drift chambers with dead regions for the beam to pass through them were used to obtain the data. Through the interference of the Coulomb and nuclear contributions to the differential cross section in the small angle region, the ratio of the real to imaginary part of the forward nuclear amplitude ..cap alpha../sub n/(0) = Ref/sub n/(0)/Imf/sub n/(0) is extracted. The importance of knowing this quantity at lower energies in order to study the differences between relativistic and non-relativistic scattering theories is discussed. 130 refs., 60 figs., 12 tabs.

  2. Limits of applicability of the concept of scattering amplitude in small-angle scattering problems

    NASA Astrophysics Data System (ADS)

    Dzheparov, F. S.; Lvov, D. V.

    2014-01-01

    The applicability of the concept of scattering amplitude to the description of small-angle scattering experiments has been considered. An expression has been obtained for a scattered radiation flux on a detector under much milder conditions than the condition of Fraunhofer diffraction. The influence of incoherence of the source on the results has been evaluated.

  3. Cryocup - Compact spherical neutron polarimetry device for small angle measurement

    NASA Astrophysics Data System (ADS)

    Wang, Tianhao

    In my thesis I describe my research work of developing a compact device for Spherical Neutron Polarimetry (SNP) measurements at small neutron scattering angles. The thesis first introduced the purpose of this research project, which is developing an easy to use and maintain version of an advanced neutron experiment technique (SNP). After the introduction, the design principle and construction detail of the prototype device is demonstrated. The design principle is based on our finite element simulation of the device's magnetic field profile, and is later verified by the performance test experiment. The prototype device is tested at the SESAME neutron beamline at Indiana University and the HB-2D beamline at Oak Ridge National laboratory. The performance test data are analyzed and proof that the design is successful and the prototype is capable of perform accurate SNP measurement. Based on the test result, the prototype device is utilized to perform SNP measurement on two types of magnetic film sample: Permalloy and Metglas. Combined with other characterization method such as SQUID and MFM, I study the magnetization of these two samples both at zero magnetic field environment and in external field. The SNP data provided by the prototype device is discussed in the thesis and provide detailed information about the magnetization, which is also not accessible through other method. In the end, the possible improvement and the future application of the device is discussed.

  4. Small-angle neutron scattering study of magnetic ordering and inhomogeneity across the martensitic phase transformation in Ni50–xCoxMn₄₀Sn₁₀ alloys

    SciTech Connect

    Bhatti, Kanwal Preet; El-Khatib, S.; Srivastava, Vijay; James, R. D.; Leighton, C.

    2012-04-27

    The Heusler-derived multiferroic alloy Ni50–xCoxMn₄₀Sn₁₀ has recently been shown to exhibit, at just above room temperature, a highly reversible martensitic phase transformation with an unusually large magnetization change. In this work the nature of the magnetic ordering above and below this transformation has been studied in detail in the critical composition range x = 6–8 via temperature-dependent (5–600 K) magnetometry and small-angle neutron scattering (SANS). We observe fairly typical paramagnetic to long-range-ordered ferromagnetic phase transitions on cooling to 420–430 K, with the expected critical spin fluctuations, followed by first-order martensitic phase transformations to a nonferromagnetic state below 360–390 K. The static magnetization reveals complex magnetism in this low-temperature nonferromagnetic phase, including a Langevin-like field dependence, distinct spin freezing near 60 K, and significant exchange bias effects, consistent with superparamagnetic blocking of ferromagnetic clusters of nanoscopic dimensions. We demonstrate that these spin clusters, whose existence has been hypothesized in a variety of martensitic alloys exhibiting competition between ferromagnetic and antiferromagnetic exchange interactions, can be directly observed by SANS. The scattering data are consistent with a liquidlike spatial distribution of interacting magnetic clusters with a mean center-to-center spacing of 12 nm. Considering the behavior of the superparmagnetism, cooling-field and temperature-dependent exchange bias, and magnetic SANS, we discuss in detail the physical form and origin of these spin clusters, their intercluster interactions, the nature of the ground-state magnetic ordering in the martensitic phase, and the implications for our understanding of such alloy systems.

  5. An overview of resid characterization by mass spectrometry and small angle scattering techniques.

    SciTech Connect

    Hunt, J. E.; Winans, R. E.

    1999-07-14

    The purpose of this presentation is to discuss what is known about the molecular structures found in petroleum resid from mass spectrometry and small angle neutron and X-ray scattering methods. The question about molecular size distributions and the occurrence of aggregation in the asphaltene fraction will be examined. Our understanding of this problem has evolved with the application of new analytical methods. Also, correlations with results from other approaches will be discussed. In addition, the issue of the nature of the heteroatom-containing molecules will be examined and the challenges that remain in this area.

  6. Using small angle solution scattering data in Xplor-NIH structure calculations.

    PubMed

    Schwieters, Charles D; Clore, G Marius

    2014-07-01

    This contribution describes the use of small and wide angle X-ray and small angle neutron scattering for biomolecular structure calculation using the program Xplor-NIH, both with and without NMR data. The current algorithms used for calculating scattering curves are described, and the use of scattering data as a structural restraint is given concrete form as a fragment of an Xplor-NIH structure calculation script. We review five examples of the use of scattering data in structure calculation, including the treatment of single domain proteins, nucleic acids, structure determination of large proteins, and the use of ensemble representations to characterize small and large amplitude motions. Published by Elsevier B.V.

  7. Structural analysis of Fe–Mn–O nanoparticles in glass ceramics by small angle scattering

    SciTech Connect

    Raghuwanshi, Vikram Singh; Harizanova, Ruzha; Tatchev, Dragomir; Hoell, Armin; Rüssel, Christian

    2015-02-15

    Magnetic nanocrystals containing Fe and Mn were obtained by annealing of silicate glasses with the composition 13.6Na{sub 2}O–62.9SiO{sub 2}–8.5MnO–15.0Fe{sub 2}O{sub 3−x} (mol%) at 580 °C for different periods of time. Here, we present Small Angle Neutron Scattering using Polarized neutrons (SANSPOL) and Anomalous Small Angle X-ray Scattering (ASAXS) investigation on these glass ceramic samples. Analysis of scattering data from both methods reveals the formation of spherical core–shell type of nanoparticles with mean sizes between 10 nm and 100 nm. ASAXS investigation shows the particles have higher concentration of iron atoms and the shell like region surrounding the particles is enriched in SiO{sub 2}. SANSPOL investigation shows the particles are found to be magnetic and are surrounded by a non-magnetic shell-like region. - Graphical abstract: Magnetic spherical core–shell nanoparticles in glass ceramics: SANSPOL and ASAXS investigations. - Highlights: • Formation and growth mechanisms of magnetic nanoparticles in silicate glass. • SANSPOL and ASAXS methods employed to evaluate quantitative information. • Analyses showed formation of nanoparticles with spherical core–shell structures. • Core of the particle is magnetic and surrounded by weak magnetic shell like region.

  8. Convex and concave successions of power-law decays in small-angle scattering

    NASA Astrophysics Data System (ADS)

    Anitas, E. M.

    2016-08-01

    The small-angle scattering (SAS) structure factor from a new model of a 3D deterministic fractal in which the relative positions and the number of structural units vary with fractal iteration number is calculated. It is shown that, depending on the relative positions of scattering units inside the fractal, we can obtain various types of power-law successions, such as: convex/concave - when the absolute value of the scattering exponent of the first power-law decay is higher/smaller than that of the subsequent power- law decay, or any combination of them (i.e. convex-concave or concave-convex). The obtained results can explain experimental SAS (neutron or X-rays) data which are characterized by a succession of power-law decays of arbitrary length.

  9. Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles

    DTIC Science & Technology

    2016-12-01

    Using Silver Nanoparticles by Frederick L Beyer Approved for public release; distribution is unlimited. NOTICES...Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles by Frederick L Beyer Weapons and Materials...2016 4. TITLE AND SUBTITLE Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles 5a. CONTRACT

  10. Small Angle X ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles

    DTIC Science & Technology

    2016-12-01

    Using Silver Nanoparticles by Frederick L Beyer Approved for public release; distribution is unlimited. NOTICES...Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles by Frederick L Beyer Weapons and Materials...2016 4. TITLE AND SUBTITLE Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles 5a. CONTRACT

  11. Effects of macromolecular crowding on the structure of a protein complex: A small-angle scattering study of superoxide dismutase

    DOE PAGES

    Rajapaksha, Ajith; Stanley, Christopher B.; Todd, Brian A.

    2015-02-17

    Macromolecular crowding can alter the structure and function of biological macromolecules. We used small angle scattering (SAS) to measure the change in size of a protein complex, superoxide dismutase (SOD), induced by macromolecular crowding. Crowding was induced using 400 MW polyethylene glycol (PEG), triethylene glycol (TEG), methyl- -glucoside ( -MG) and trimethylamine N-oxide (TMAO). Parallel small angle neutron scattering (SANS) and small angle x-ray scattering (SAXS) allowed us to unambiguously attribute apparent changes in radius of gyration to changes in the structure of SOD. For a 40% PEG solution, we find that the volume of SOD was reduced by 9%.more » Considering the osmotic pressure due to PEG, this deformation corresponds to a highly compressible structure. SAXS done in the presence of TEG suggests that for further deformation beyond a 9% decrease in volume the resistance to deformation may increase dramatically.« less

  12. Nanostructure surveys of macroscopic specimens by small-angle scattering tensor tomography

    NASA Astrophysics Data System (ADS)

    Liebi, Marianne; Georgiadis, Marios; Menzel, Andreas; Schneider, Philipp; Kohlbrecher, Joachim; Bunk, Oliver; Guizar-Sicairos, Manuel

    2015-11-01

    The mechanical properties of many materials are based on the macroscopic arrangement and orientation of their nanostructure. This nanostructure can be ordered over a range of length scales. In biology, the principle of hierarchical ordering is often used to maximize functionality, such as strength and robustness of the material, while minimizing weight and energy cost. Methods for nanoscale imaging provide direct visual access to the ultrastructure (nanoscale structure that is too small to be imaged using light microscopy), but the field of view is limited and does not easily allow a full correlative study of changes in the ultrastructure over a macroscopic sample. Other methods of probing ultrastructure ordering, such as small-angle scattering of X-rays or neutrons, can be applied to macroscopic samples; however, these scattering methods remain constrained to two-dimensional specimens or to isotropically oriented ultrastructures. These constraints limit the use of these methods for studying nanostructures with more complex orientation patterns, which are abundant in nature and materials science. Here, we introduce an imaging method that combines small-angle scattering with tensor tomography to probe nanoscale structures in three-dimensional macroscopic samples in a non-destructive way. We demonstrate the method by measuring the main orientation and the degree of orientation of nanoscale mineralized collagen fibrils in a human trabecula bone sample with a spatial resolution of 25 micrometres. Symmetries within the sample, such as the cylindrical symmetry commonly observed for mineralized collagen fibrils in bone, allow for tractable sampling requirements and numerical efficiency. Small-angle scattering tensor tomography is applicable to both biological and materials science specimens, and may be useful for understanding and characterizing smart or bio-inspired materials. Moreover, because the method is non-destructive, it is appropriate for in situ measurements and

  13. Nanostructure surveys of macroscopic specimens by small-angle scattering tensor tomography.

    PubMed

    Liebi, Marianne; Georgiadis, Marios; Menzel, Andreas; Schneider, Philipp; Kohlbrecher, Joachim; Bunk, Oliver; Guizar-Sicairos, Manuel

    2015-11-19

    The mechanical properties of many materials are based on the macroscopic arrangement and orientation of their nanostructure. This nanostructure can be ordered over a range of length scales. In biology, the principle of hierarchical ordering is often used to maximize functionality, such as strength and robustness of the material, while minimizing weight and energy cost. Methods for nanoscale imaging provide direct visual access to the ultrastructure (nanoscale structure that is too small to be imaged using light microscopy), but the field of view is limited and does not easily allow a full correlative study of changes in the ultrastructure over a macroscopic sample. Other methods of probing ultrastructure ordering, such as small-angle scattering of X-rays or neutrons, can be applied to macroscopic samples; however, these scattering methods remain constrained to two-dimensional specimens or to isotropically oriented ultrastructures. These constraints limit the use of these methods for studying nanostructures with more complex orientation patterns, which are abundant in nature and materials science. Here, we introduce an imaging method that combines small-angle scattering with tensor tomography to probe nanoscale structures in three-dimensional macroscopic samples in a non-destructive way. We demonstrate the method by measuring the main orientation and the degree of orientation of nanoscale mineralized collagen fibrils in a human trabecula bone sample with a spatial resolution of 25 micrometres. Symmetries within the sample, such as the cylindrical symmetry commonly observed for mineralized collagen fibrils in bone, allow for tractable sampling requirements and numerical efficiency. Small-angle scattering tensor tomography is applicable to both biological and materials science specimens, and may be useful for understanding and characterizing smart or bio-inspired materials. Moreover, because the method is non-destructive, it is appropriate for in situ measurements and

  14. Solution structures of calcium regulating proteins: A small-angle scattering study

    SciTech Connect

    Trewhella, J.; Heidorn, D.B.; Seeger, P.A.

    1987-11-01

    Small-angle X-ray scattering (SAXS) experiments have shown that the solution structures of two calcium-binding regulatory proteins, calmodulin and troponin C, are significantly different from their crystal structure forms. The structural differences occur in a region of calmodulin that is thought to bind to target enzymes;the calmodulin-enzyme complex is an initiator for many important biochemical processes. Calcium binding to calmodulin induces a conformational change that is a prerequisite for calmodulin binding to a target enzyme. SAXS data can characterize this conformational change and give insight into the mechanism of enzyme binding. Neutron resonance scattering promises to determine accurately the distances between calcium binding sites, thus providing important constraints on the structure of calmodulin in solution. 24 refs., 5 figs., 1 tab.

  15. The solution structure of stilbenoid dendrimers: a small-angle scattering study.

    PubMed

    Rosenfeldt, Sabine; Karpuk, Elena; Lehmann, Matthias; Meier, Herbert; Lindner, Peter; Harnau, Ludger; Ballauff, Matthias

    2006-10-13

    The spatial structure of a stilbenoid dendrimer is investigated by small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) in dilute solution. All measurements are performed in toluene. The dendrimer consists of a stilbenoid scaffold with appended hexyloxy chains. SAXS is mainly sensitive to the dendrimer scaffold whereas SANS intensity, measured in fully deuterated toluene, derives from the solute molecules. The resulting SAXS and SANS intensities are analyzed by comparison with various models. It is found that the model of a circular disk gives the best description of the data. SAXS data demonstrate that the stilbenoid scaffold is flat as expected for benzene rings conjugated through vinylene units. Thus, it can be described by a circular disk with a radius of 1.6 nm and a thickness of 0.7 nm. SANS, on the other hand, shows that the hexyloxy chains are not confined in the plane defined by the core. This is derived from modeling the SANS data with a much thicker circular disk (radius: 2.4 nm, thickness: 1.8 nm). The structure factor S(q), describing the interaction of the dendrimers at higher concentrations, is modeled quantitatively with the "polymer reference interaction site model" (PRISM) integral equation formalism for hard plates such as particles. Here the structural data obtained from the analysis of the SANS data are used so that no new adjustable parameter is necessary for this description.

  16. Morphological characterization of carbon-nanofiber-reinforced epoxy nanocomposites using ultra-small angle scattering

    SciTech Connect

    Justice, R.S.; Anderson, D.P.; Brown, J.M.; Arlen, M.J.; Colleary, A.J.; Lafdi, K.; Schaefer, D.W.

    2010-07-01

    Studies of the properties of nanocomposites reinforced with vapor-grown carbon nanofibers (VGCFs) can be found throughout the literature. Electrical, mechanical, viscoelastic, and rheological properties are just a few of the characteristics that have been well discussed. Although these properties depend on morphology, morphological characterization is rare. Due to its 2-dimensional nature, microscopy is of limited value when analyzing network morphologies. This work will show how the characterization of the three-dimensional geometry and network formation of VGCFs can be determined using ultra-small angle scattering techniques. Ultra-small angle x-ray and neutron scattering (USAXS and USANS) were used to characterize the morphology of carbon nanofibers suspended in epoxy. Using a simplified tube model, we estimate the dimensions of suspended fibers. The assumption of tubular fibers accounts for the increased surface area observed with USAXS that is not accounted for using a solid rod model. Furthermore, USANS was used to search for a structural signature associated with the electrical percolation threshold. USANS extends to longer dimensional scales than USAXS, which measures a smaller range of momentum transfer. To determine the electrical percolation threshold, AC impedance spectroscopy was employed to verify that an electrically conductive, percolated network forms at VGCNF loadings of 0.8% < CNF wt% < 1.2%. These values correlate with the USANS data, where a morphological transition is seen at {approx}1.2% loading.

  17. Glassy carbon as an absolute intensity calibration standard for small-angle scattering.

    SciTech Connect

    Zhang, F.; Ilavsky, J.; Long, G.; Allen, A.; Quintana, J.; Jemian, P.; NIST

    2010-05-01

    Absolute calibration of small-angle scattering (SAS) intensity data (measured in terms of the differential scattering cross section per unit sample volume per unit solid angle) is essential for many important aspects of quantitative SAS analysis, such as obtaining the number density, volume fraction, and specific surface area of the scatterers. It also enables scattering data from different instruments (light, X-ray, or neutron scattering) to be combined, and it can even be useful to detect the existence of artifacts in the experimental data. Different primary or secondary calibration methods are available. In the latter case, absolute intensity calibration requires a stable artifact with the necessary scattering profile. Glassy carbon has sometimes been selected as this intensity calibration standard. Here we review the spatial homogeneity and temporal stability of one type of commercially available glassy carbon that is being used as an intensity calibration standard at a number of SAS facilities. We demonstrate that glassy carbon is sufficiently homogeneous and stable during routine use to be relied upon as a suitable standard for absolute intensity calibration of SAS data.

  18. New developments in the ATSAS program package for small-angle scattering data analysis

    PubMed Central

    Petoukhov, Maxim V.; Franke, Daniel; Shkumatov, Alexander V.; Tria, Giancarlo; Kikhney, Alexey G.; Gajda, Michal; Gorba, Christian; Mertens, Haydyn D. T.; Konarev, Petr V.; Svergun, Dmitri I.

    2012-01-01

    New developments in the program package ATSAS (version 2.4) for the processing and analysis of isotropic small-angle X-ray and neutron scattering data are described. They include (i) multiplatform data manipulation and display tools, (ii) programs for automated data processing and calculation of overall parameters, (iii) improved usage of high- and low-resolution models from other structural methods, (iv) new algorithms to build three-dimensional models from weakly interacting oligomeric systems and complexes, and (v) enhanced tools to analyse data from mixtures and flexible systems. The new ATSAS release includes installers for current major platforms (Windows, Linux and Mac OSX) and provides improved indexed user documentation. The web-related developments, including a user discussion forum and a widened online access to run ATSAS programs, are also presented. PMID:25484842

  19. Small-angle Scattering Study of Mesoscopic Structures in Charged Gel and Their Evolution in Dehydration

    SciTech Connect

    Sugiyama, M.; Annaka, M.; Hara, K.; Vigild, M. E.; Wignall, George D

    2003-01-01

    Mesoscopic structures, with length scales {approx}10{sup 2} {angstrom}, were investigated by small-angle X-ray and neutron scattering (SAXS and SANS) in several N-isopropylacrylamide-sodium acrylate (NIPA-SA) copolymeric hydrogels with varying [NIPA]/[SA] ratios and water contents. The SAXS experiments reveal that, depending upon the [NIPA]/[SA] ratio, the dehydrated NIPA-SA gel shows two mesoscopic structures: one consists of randomly distributed SA-rich islands in NIPA matrix, while the other is a microphase-separated structure, composed of NIPA-rich and SA-rich domains. In addition, the SANS experiments reveal the mesoscopic structural features during the dehydration process. As the concentration of the network polymers increases, NIPA-rich and water-rich domains segregate in the gel. Then, an electrostatic interaction between the segregated domains induces a microphase-separated structure in the limit of the dehydrated NIPA-SA gel.

  20. Multiple size scale structures in silica/siloxane composites studied by small-angle scattering

    SciTech Connect

    Beaucage, G.; Schaefer, D.W.; Ulibarri, T.; Black, E.

    1993-12-31

    The physical properties of in-situ produced composites, such as the TEOS-polysiloxane based systems, are directly related to the complex interaction of structural features from the nano- to macro-scopic scales. The nature of these structural interactions are a key element in understanding and controlling mechanical properties in these systems. We believe that the smallest scale structures, in the nanometer range, correlate with properties such as the modulus while large-scale structures on the micron scale effect failure in these materials. This paper discusses techniques for analysis of structural features and interrelation of structural features over these wide ranges of size using small-angle light, x-ray and neutron scattering. Combination of data from different instruments allows for characterization of the interaction between these different size scale features.

  1. Small-angle scattering as a tool to study the thermal denaturation of DNA

    NASA Astrophysics Data System (ADS)

    Wood, Kathleen; Knott, Robert; Tonchev, Ognyan; Angelov, Dimitar; Theodorakopoulos, Nikos; Peyrard, Michel

    2014-10-01

    DNA thermal denaturation is the breaking of the base pairs, leading to a splitting of the two strands of the double helix. While it is easy to measure the fraction of open base pairs (f) vs. temperature, determining the fraction (p) of fully open molecules is much harder. Previously, the simultaneous recording of f and p could only be achieved for special sequences. We show that small-angle scattering of X-rays or neutrons allows the measurement of p for any sequence. We illustrate the method with a SAXS investigation of two sequences designed to exhibit different melting profiles and compare the SAXS data with nano-calorimetric measurements of the melting curve.

  2. Toward a Taxonomy of the Denatured State: Small Angle Scattering Studies of Unfolded Proteins

    SciTech Connect

    Millett, I.S.; Doniach, S.; Plaxco, K.W.

    2005-02-15

    Despite the critical role the unfolded state plays in defining protein folding kinetics and thermodynamics (Berg et al., 2002; Dunker, 2002; Shortle, 2002; Wright and Dyson, 2002), our understanding of its detailed structure remains rather rudimentary; the heterogeneity of the unfolded ensemble renders difficult or impossible its study by traditional, atomic-level structural methods. Consequently, recent years have seen a significant expansion of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) techniques that provide direct, albeit rotationally and time-averaged, measures of the geometric properties of the unfolded ensemble. These studies have reached a critical mass, allowing us for the first time to define general observations regarding the nature of the geometry - and possibly the chemistry and physics - of unfolded proteins.

  3. The contribution of small angle and quasi-elastic scattering to the physics of liquid water

    NASA Astrophysics Data System (ADS)

    Teixeira, José

    2017-05-01

    Many properties of liquid water at low temperature show anomalous behaviour. For example, density, isothermal compressibility, heat capacity pass by maxima or minima and transport properties show a super-Arrhenius behaviour. Extrapolations performed beyond the homogeneous nucleation temperature are at the origin of models that predict critical points, liquid-liquid transitions or dynamic cross-overs in the large domain of temperature and pressure not accessible to experiments because of ice nucleation. A careful analysis of existing data can be used to test some of these models. Small angle X-ray or neutron scattering data are incompatible with models where two liquids or heterogeneities are present. Quasi-elastic neutron scattering, taking advantage and combining both coherent and incoherent scattering show that two relaxation times are present in liquid water and that one of them, related to hydrogen bond dynamics, has an Arrhenian behaviour, suggesting that the associated dynamics of the bonds, similar to the β relaxation of polymers, determines the glass transition temperature of water.

  4. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering

    PubMed Central

    Zhang, Fan; Kline, R. Joseph; Guthrie, William F.; Ilavsky, Jan

    2017-01-01

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008–0.25 Å−1, together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments that employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. The validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification. PMID:28381972

  5. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering

    DOE PAGES

    Allen, Andrew J.; Zhang, Fan; Kline, R. Joseph; ...

    2017-03-07

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008–0.25 Å–1, together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments that employmore » a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. As a result, the validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.« less

  6. Small Angle X-ray Scattering for Nanoparticle Research

    SciTech Connect

    Lee, Byeongdu; Senesi-Good, Andrew J.; Li, Tao

    2016-09-28

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and ångström length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle’s size, size distribution, shape, and organization into hierarchal structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well the combination of SAXS with other X-ray and non-X ray characterization tools. We conclude with an examination of several key areas of research where X-rays scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and in operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.

  7. Small Angle X-ray Scattering for Nanoparticle Research

    SciTech Connect

    Li, Tao; Senesi, Andrew J.; Lee, Byeongdu

    2016-04-07

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and ångström length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle’s size, size distribution, shape, and organization into hierarchal structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well the combination of SAXS with other X-ray and non-X ray characterization tools. Furthermore, we conclude with an examination of several key areas of research where X-rays scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and in operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.

  8. Small Angle X-ray Scattering for Nanoparticle Research

    DOE PAGES

    Li, Tao; Senesi, Andrew J.; Lee, Byeongdu

    2016-04-07

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and ångström length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle’s size, size distribution,more » shape, and organization into hierarchal structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well the combination of SAXS with other X-ray and non-X ray characterization tools. Furthermore, we conclude with an examination of several key areas of research where X-rays scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and in operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.« less

  9. Small Angle X-ray Scattering for Nanoparticle Research.

    PubMed

    Li, Tao; Senesi, Andrew J; Lee, Byeongdu

    2016-09-28

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and angstrom length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle's size, size distribution, shape, and organization into hierarchical structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well as the combination of SAXS with other X-ray and non-X-ray characterization tools. We conclude with an examination of several key areas of research where X-ray scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.

  10. Monte Carlo calculation of large and small-angle electron scattering in air

    DOE PAGES

    Cohen, B. I.; Higginson, D. P.; Eng, C. D.; ...

    2017-08-12

    A Monte Carlo method for angle scattering of electrons in air that accommodates the small-angle multiple scattering and larger-angle single scattering limits is introduced. In this work, the algorithm is designed for use in a particle-in-cell simulation of electron transport and electromagnetic wave effects in air. The method is illustrated in example calculations.

  11. Small-angle Compton Scattering to Determine the Depth of a Radioactive Source in Matter

    SciTech Connect

    Oberer, R. B.; Gunn, C. A.; Chiang, L. G.; Valiga, R. E.; Cantrell, J. A.

    2011-04-01

    A gamma-ray peak in a spectrum is often accompanied by a discontinuity in the Compton continuum at the peak. The Compton continuum results from Compton scattering in the detector. The discontinuity at a peak results from small-angle Compton scattering by the gamma rays in matter situated directly between the gamma-ray source and the detector. The magnitude of this discontinuity with respect to the gamma-ray peak is therefore an indicator of the amount of material or shielding between the gamma-ray source and the detector. This small-angle scattering was used to determine the depth of highly-enriched uranium (HEU) solution standards in a concrete floor mockup. The empirical results of the use of this small-angle scattering discontinuity in a concrete floor experiment will be described. A Monte Carlo calculation of the experiment will also be described. In addition, the depth determined from small-angle scattering was used in conjunction with differential attenuation to more accurately measure the uranium content of the mockup. Following these empirical results, the theory of small-angle scattering will be discussed. The magnitude of the discontinuity compared to the peak count rate is directly related to the depth of the gamma-ray source in matter. This relation can be described by relatively simple mathematical expressions. This is the first instance that we are aware of in which the small-angle Compton scattering has been used to determine the depth of a radioactive source. Furthermore this is the first development of the theoretical expressions for the magnitude of the small-angle scattering discontinuity.

  12. Small-angle scattering of dense, polydisperse granular porous media: Computation free of size effects

    NASA Astrophysics Data System (ADS)

    Brisard, Sébastien; Levitz, Pierre

    2013-01-01

    Small-angle x-ray and neutrons scattering is a widespread experimental tool for the investigation of the microstructure of random heterogeneous materials. Validation of (computer-generated) model microstructures often requires the numerical computation of the scattering intensity, which must be carried out with great care due to finite size effects. In this paper, a new method for this computation is presented. It is superior to previously existing methods for three reasons: First, it applies to any type of microstructure (not necessarily granular). Second, closed-form expressions of the size effects inherent to the proposed method can be rigorously derived and removed (in this sense, our method is free of size effects). Third, the complexity of the new algorithm is linear and the computation can easily be updated to account for local changes of the microstructure, while most existing algorithms are quadratic and any change of the microstructure requires a full recomputation. The present paper provides full derivation and validation of this method. Application to the computation of the scattering intensity of dense, polydisperse assemblies of spheres is then presented. A new, simple algorithm for the generation of these dense configurations is introduced. Finally, the results are critically reviewed in the perspective of hardened cement pastes.

  13. How Random are Intrinsically Disordered Proteins? A Small Angle Scattering Perspective

    PubMed Central

    Receveur-Bréchot, Véronique; Durand, Dominique

    2012-01-01

    While the crucial role of intrinsically disordered proteins (IDPs) in the cell cycle is now recognized, deciphering their molecular mode of action at the structural level still remains highly challenging and requires a combination of many biophysical approaches. Among them, small angle X-ray scattering (SAXS) has been extremely successful in the last decade and has become an indispensable technique for addressing many of the fundamental questions regarding the activities of IDPs. After introducing some experimental issues specific to IDPs and in relation to the latest technical developments, this article presents the interest of the theory of polymer physics to evaluate the flexibility of fully disordered proteins. The different strategies to obtain 3-dimensional models of IDPs, free in solution and associated in a complex, are then reviewed. Indeed, recent computational advances have made it possible to readily extract maximum information from the scattering curve with a special emphasis on highly flexible systems, such as multidomain proteins and IDPs. Furthermore, integrated computational approaches now enable the generation of ensembles of conformers to translate the unique flexible characteristics of IDPs by taking into consideration the constraints of more and more various complementary experiment. In particular, a combination of SAXS with high-resolution techniques, such as x-ray crystallography and NMR, allows us to provide reliable models and to gain unique structural insights about the protein over multiple structural scales. The latest neutron scattering experiments also promise new advances in the study of the conformational changes of macromolecules involving more complex systems. PMID:22044150

  14. Small-angle approximation to the transfer of narrow laser beams in anisotropic scattering media

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Deepak, A.

    1981-01-01

    The broadening and the signal power detected of a laser beam traversing an anisotropic scattering medium were examined using the small-angle approximation to the radiative transfer equation in which photons suffering large-angle deflections are neglected. To obtain tractable answers, simple Gaussian and non-Gaussian functions for the scattering phase functions are assumed. Two other approximate approaches employed in the field to further simplify the small-angle approximation solutions are described, and the results obtained by one of them are compared with those obtained using small-angle approximation. An exact method for obtaining the contribution of each higher order scattering to the radiance field is examined but no results are presented.

  15. SCT: a suite of programs for comparing atomistic models with small-angle scattering data.

    PubMed

    Wright, David W; Perkins, Stephen J

    2015-06-01

    Small-angle X-ray and neutron scattering techniques characterize proteins in solution and complement high-resolution structural studies. They are of particular utility when large proteins cannot be crystallized or when the structure is altered by solution conditions. Atomistic models of the averaged structure can be generated through constrained modelling, a technique in which known domain or subunit structures are combined with linker models to produce candidate global conformations. By randomizing the configuration adopted by the different elements of the model, thousands of candidate structures are produced. Next, theoretical scattering curves are generated for each model for trial-and-error fits to the experimental data. From these, a small family of best-fit models is identified. In order to facilitate both the computation of theoretical scattering curves from atomistic models and their comparison with experiment, the SCT suite of tools was developed. SCT also includes programs that provide sequence-based estimates of protein volume (either incorporating hydration or not) and add a hydration layer to models for X-ray scattering modelling. The original SCT software, written in Fortran, resulted in the first atomistic scattering structures to be deposited in the Protein Data Bank, and 77 structures for antibodies, complement proteins and anionic oligosaccharides were determined between 1998 and 2014. For the first time, this software is publicly available, alongside an easier-to-use reimplementation of the same algorithms in Python. Both versions of SCT have been released as open-source software under the Apache 2 license and are available for download from https://github.com/dww100/sct.

  16. Resolution of ab initio shapes determined from small-angle scattering

    PubMed Central

    Tuukkanen, Anne T.; Kleywegt, Gerard J.; Svergun, Dmitri I.

    2016-01-01

    Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models. PMID:27840683

  17. Resolution of ab initio shapes determined from small-angle scattering.

    PubMed

    Tuukkanen, Anne T; Kleywegt, Gerard J; Svergun, Dmitri I

    2016-11-01

    Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models.

  18. QUAFIT: A Novel Method for the Quaternary Structure Determination from Small-Angle Scattering Data

    PubMed Central

    Spinozzi, Francesco; Beltramini, Mariano

    2012-01-01

    The new QUAFIT method for determining the quaternary structure of biological macromolecular assemblies by analyzing x-ray or neutron small-angle scattering data is presented. The method is based on the idea that asymmetric monomers, formed by rigid domains of known atomic structure possibly connected by flexible linkers of known sequence, are assembled according to a point-group symmetry combined with a screw axis. Scattering amplitudes of domains and linkers are determined by means of a spherical harmonics expansion and combined to get the form factor of the assembly. To avoid any overlap among domains, the contact distance between two asymmetric domains is determined as a function of their orientation by a new algorithm, based on Stone’s Invariants expansion. To account for continuity and compactness of the whole assembly, an anisotropic Lennard-Jones potential among domains, written in terms of the contact distances, is included in the merit function. QUAFIT allows for the simultaneous presence of oligomerization intermediates as well as of monomers distributed over multiple conformations. QUAFIT has been tested by studying the structure of a high molecular weight protein, the hemocyanin from Octopus vulgaris, under solution conditions that stabilize the decameric form or induce dissociation into monomers, respectively. Results are in very good agreement with the structural model derived from electron microscopy observations. PMID:22947867

  19. Studying fractal geometry on submicron length scales by small-angle scattering

    SciTech Connect

    Wong, P.; Lin, J.

    1988-08-01

    Recent studies have shown that internal surfaces of porous geological materials, such as rocks and lignite coals, can be described by fractals down to atomic length scales. In this paper, the basic properties of self-similar and self-affine fractals are reviewed and how fractal dimensions can be measured by small-angle scattering experiments are discussed.

  20. PREFACE Proceedings of the XIV International Conference on Small-Angle Scattering, SAS-2009

    NASA Astrophysics Data System (ADS)

    King, Stephen; Terrill, Nicholas

    2010-10-01

    The XIV International Conference on Small-Angle Scattering, SAS-2009, was held in Oxford UK, 13-18 September 2009, and was jointly organised under the auspices of the International Union of Crystallography Commission on SAS by a team from the Diamond Light Source and the ISIS Pulsed Neutron Source - their first such joint venture - with help from the UK Science and Technology Facilities Council. It was the first time that this long running and successful series of conferences on the application, science and technology of small-angle scattering techniques had been staged in the UK. The UK has a proud heritage in small-angle scattering: as home to one of the world's first SANS instruments (at AERE Harwell), as the site of the world's first 2nd generation X-ray Synchrotron (the SRS at Daresbury with its suite of SAXS beamlines), and latterly as the location of the world's most successful pulsed source SANS instrument. Indeed, 2009 also marked the 25th Anniversary of neutron operations at ISIS and the opening of a Second Target Station. Whilst the SRS ceased operations in 2008, its mantle has been inherited by the Diamond synchrotron. Many delegates took the opportunity to visit both Diamond and ISIS during a conference excursion. Despite the prevailing global economic downturn, we were delighted that 434 delegates from 32 different countries were able to attend SAS-2009; two-thirds were drawn from the UK, Germany, Japan, the USA and France, but there were also sizeable contingents from Australia, Korea, Taiwan and South America. In many ways this geographical spread reflects the present and emerging distribution, respectively, of 3rd generation X-ray synchrotrons and high-flux neutron sources, although the scope of the conference was not solely limited to these probes. Financial support from the IUCr enabled us to grant bursaries to attend SAS-2009 to 12 delegates from emerging countries (Algeria, Argentina, Brazil, India, Nepal, Romania, Russia and the Ukraine). The

  1. X-ray small-angle scattering from sputtered CeO{sub 2}/C bilayers

    SciTech Connect

    Haviar, S.; Dubau, M.; Khalakhan, I.; Vorokhta, M.; Matolinova, I.; Matolin, V.; Vales, V.; Endres, J.; Holy, V.; Buljan, M.; Bernstorff, S.

    2013-01-14

    Surface and interface morphology of cerium oxide/carbon bilayers used as thin-film catalysts is studied by grazing-incidence small-angle x-ray scattering, scanning electron microscopy, and atomic-force microscopy, and the dependence of the structural parameters on the thicknesses of the constituting layers is investigated. The applicability of x-ray scattering and its advantages over standard analytical methods are discussed.

  2. [Construction of a small angle neutron scattering spectrometer for investigation of microemulsions and micellar solutions in bulk, in porous materials and under shear]. Progress report [Phase 1, July 1, 1990--June 30, 1993

    SciTech Connect

    Not Available

    1993-09-01

    This report presents the status of the small-angle diffractometer; 3-D microstructure of bicontinuous microemulsions from SANS and simulation; local geometry of the surfactant monolayer in microemulsions; surface ordering in microemulsions; dynamics of water-in-oil droplet microemulsions; and micellar formation and correlation in the cavity of porous silica glass.

  3. BIOISIS: Biological Macromolecules by Small Angle X-ray Scattering (SAXS)

    DOE Data Explorer

    Tainer, John [Scripps Research Institute; Hura, Greg [LBNL; Rambo, Robert P. [LBNL

    BIOISIS is an open access database dedicated to the study of biological macromolecules by small angle X-ray scattering (SAXS). BIOISIS aims to become the complete source for the deposition, distribution and maintenance of small angle X-ray scattering data and technologies. The database is designed around the concept of an ôexperimentö and relates a specific experiment to a set of genes, organisms, computational models and experimental data. As of May 2012, BIOSIS contains 7,118 genes covering four different organisms. Forty-two modeled structures are available. Clicking on a structures reveals scattering curves, experimental conditions, and experimental values. The data are collected at Beamline 12.3.1 of the Advanced Light Source (ALS).[Copied with editing from http://www.bioisis.net/about

  4. A preliminary study of breast cancer diagnosis using laboratory based small angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Round, A. R.; Wilkinson, S. J.; Hall, C. J.; Rogers, K. D.; Glatter, O.; Wess, T.; Ellis, I. O.

    2005-09-01

    Breast tissue collected from tumour samples and normal tissue from bi-lateral mastectomy procedures were examined using small angle x-ray scattering. Previous work has indicated that breast tissue disease diagnosis could be performed using small angle x-ray scattering (SAXS) from a synchrotron radiation source. The technique would be more useful to health services if it could be made to work using a conventional x-ray source. Consistent and reliable differences in x-ray scatter distributions were observed between samples from normal and tumour tissue samples using the laboratory based 'SAXSess' system. Albeit from a small number of samples, a sensitivity of 100% was obtained. This result encourages us to pursue the implementation of SAXS as a laboratory based diagnosis technique.

  5. Quantitative characterization of the contrast mechanisms of ultra-small angle x-ray scattering imaging.

    SciTech Connect

    Zhang, F.; Long, G. G.; Levine, L.E.; Ilavsky, J.; Jemain, P.R.; NIST

    2008-04-01

    A general treatment of X-ray imaging contrast for ultra-small-angle X-ray scattering (USAXS) imaging is presented; this approach makes use of phase propagation and dynamical diffraction theory to account quantitatively for the intensity distribution at the detector plane. Simulated results from a model system of micrometer-sized spherical SiO{sub 2} particles embedded in a polypropylene matrix show good agreement with experimental measurements. Simulations by means of a separate geometrical ray-tracing method also account for the features in the USAXS images and offer a complementary view of small-angle X-ray scattering as a contrast mechanism. The ray-tracing analysis indicates that refraction, in the form of Porod scattering, and, to a much lesser extent, X-ray reflection account for the USAXS imaging contrast.

  6. Small-angle and surface scattering from porous and fractal materials.

    SciTech Connect

    Sinha, S. K.

    1998-09-18

    We review the basic theoretical methods used to treat small-angle scattering from porous materials, treated as general two-phase systems, and also the basic experimental techniques for carrying out such experiments. We discuss the special forms of the scattering when the materials exhibit mass or surface fractal behavior, and review the results of recent experiments on several types of porous media and also SANS experiments probing the phase behavior of binary fluid mixtures or polymer solutions confined in porous materials. Finally, we discuss the analogous technique of off-specular scattering from surfaces and interfaces which is used to study surface roughness of various kinds.

  7. Quaternary structure built from subunits combining NMR and small-angle x-ray scattering data.

    PubMed Central

    Mattinen, Maija-Liisa; Pääkkönen, Kimmo; Ikonen, Teemu; Craven, Jeremy; Drakenberg, Torbjörn; Serimaa, Ritva; Waltho, Jonathan; Annila, Arto

    2002-01-01

    A new principle in constructing molecular complexes from the known high-resolution domain structures joining data from NMR and small-angle x-ray scattering (SAXS) measurements is described. Structure of calmodulin in complex with trifluoperazine was built from N- and C-terminal domains oriented based on residual dipolar couplings measured by NMR in a dilute liquid crystal, and the overall shape of the complex was derived from SAXS data. The residual dipolar coupling data serves to reduce angular degrees of freedom, and the small-angle scattering data serves to confine the translational degrees of freedom. The complex built by this method was found to be consistent with the known crystal structure. The study demonstrates how approximate tertiary structures of modular proteins or quaternary structures composed of subunits can be assembled from high-resolution structures of domains or subunits using mutually complementary NMR and SAXS data. PMID:12124297

  8. Small-angle X-ray scattering method to characterize molecular interactions: Proof of concept.

    PubMed

    Allec, Nicholas; Choi, Mina; Yesupriya, Nikhil; Szychowski, Brian; White, Michael R; Kann, Maricel G; Garcin, Elsa D; Daniel, Marie-Christine; Badano, Aldo

    2015-07-10

    Characterizing biomolecular interactions is crucial to the understanding of biological processes. Existing characterization methods have low spatial resolution, poor specificity, and some lack the capability for deep tissue imaging. We describe a novel technique that relies on small-angle X-ray scattering signatures from high-contrast molecular probes that correlate with the presence of biomolecular interactions. We describe a proof-of-concept study that uses a model system consisting of mixtures of monomer solutions of gold nanoparticles (GNPs) as the non-interacting species and solutions of GNP dimers linked with an organic molecule (dimethyl suberimidate) as the interacting species. We report estimates of the interaction fraction obtained with the proposed small-angle X-ray scattering characterization method exhibiting strong correlation with the known relative concentration of interacting and non-interacting species.

  9. SFF analysis of the small angle scattering data for investigation of a vesicle systems structure

    NASA Astrophysics Data System (ADS)

    Zemlyanaya, E. V.; Kiselev, M. A.; Zhabitskaya, E. I.; Gruzinov, A. Yu.; Aksenov, V. L.; Ipatova, O. M.; Druzhilovskaya, O. S.

    2016-06-01

    Experimental data on the small angle synchrotron X-ray scattering (SAXS) are analyzed on a basis of Separated form factors method (SFF) for a study of the drug delivery Phospholipid Transport Nano System (PTNS). Basic parameters of polydispersed population of PTNS nanoparticles (average radius of PTNS-particles, polydispersity of radius, thickness of membrane) have been determined. The results are discussed in comparison with the SFF results for the “classical” vesicular system of dimyristoylphosphocholine (DMPC).

  10. Changes of creatine kinase structure upon ligand binding as seen by small-angle scattering

    NASA Astrophysics Data System (ADS)

    Forstner, Michael; Kriechbaum, Manfred; Laggner, Peter; Wallimann, Theo

    1996-09-01

    Small-angle X-ray and neutron scattering have been used to investigate structural changes upon binding of individual substrates or a transition state analogue complex (TSAC), consisting of Mg-ADP, creatine and KNO 3 to creatine kinase isoenzymes (dimeric M-CK and octameric Mi-CK) and monomeric arginine kinase (AK). Considerable changes in the shape and the size of the molecules occurred upon binding of Mg-ATP and TSAC, whereas creatine alone had only a small effect. In Mi-CK, the radius of gyration was reduced from 55.6 Å (free enzyme) to 48.9 Å (enzyme + Mg-ATP) and to 48.2 Å (enzyme + TSAC). The experiments performed with M-CK showed similar changes from 28.0 Å (free enzyme) to 25.6 Å (enzyme + Mg-ATP) and to 25.5 Å (enzyme + TSAC). Creatine alone did not lead to significant changes in the radii of gyration, nor did free ATP or ADP. AK showed the same behaviour: a change of the radius of gyration from 21.5 Å (free enzyme) to 19.7 Å (enzyme + MG-ATP), whereas with arginine alone only a minor change could be observed. The primary change in structure as seen with monomeric AK seems to be a magnesium-nucleotide induced domain movement relative to each other, whereas the effect of substrate may be of local order only. In creatine kinase, however, further movements must be involved in the large conformational change.

  11. Small-angle scatter tomography with a photon-counting detector array

    NASA Astrophysics Data System (ADS)

    Pang, Shuo; Zhu, Zheyuan; Wang, Ge; Cong, Wenxiang

    2016-05-01

    Small-angle x-ray scatter imaging has a high intrinsic contrast in cancer research and other applications, and provides information on molecular composition and micro-structure of the tissue. In general, the implementations of small-angle coherent scatter imaging can be divided into two main categories: direct tomography and angular dispersive computerized tomography. Based on the recent development of energy-discriminative photon-counting detector array, here we propose a computerized tomography setup based on energy-dispersive measurement with a photon-counting detector array. To show merits of the energy-dispersive approach, we have performed numerical tests with a phantom containing various tissue types, in comparison with the existing imaging approaches. The results show that with an energy resolution of ~6 keV, the energy dispersive tomography system with a broadband tabletop x-ray would outperform the angular dispersive system, which makes the x-ray small-angle scatter tomography promising for high-specificity tissue imaging.

  12. The potential for studying the effects of microgravity on connective tissue by small angle light scattering

    NASA Astrophysics Data System (ADS)

    McNamara, K.; Bellare, A.; Shortkroff, S.; Dahlgren, E.

    In order to address the effects of microgravity on living tissue, we must examine and understand tissue response on a molecular level. Doing so requires the development of quantitative techniques for characterizing tissue behavior on the micrometer scale under both normal and reduced gravitational fields. It has been demonstrated that small angle light scattering holds great promise in this regard. Small angle light scattering (SALS) has been used to probe tissue microstructure on the micron and sub-micron length scales. Quantitative information on feature geometry, dimension and orientation was obtained. Here, we discuss the application of small angle light scattering techniques to the study of connective tissue. Two terrestrial situations relevant to future microgravity studies were considered: the anisotropic behavior of collagen fibers in rabbit tendon in response to increasing load; and, the variation in collagen structure in healthy and arthritic human cartilage. SALS allowed quantitative determination of both fiber diameter and degree of orientation, providing a level of information beyond that obtainable by light and electron microscopies. The primary advantages of SALS over these techniques lies in its quantitative nature and reduced sample preparation requirements. SALS requires neither vacuum or the use of dyes, eliminating important potential sources of artifacts. Results from these studies compare favorably with microscopy studies and demonstrate the importance of the quantitative nature of the technique. In addition, these results also demonstrate the potential of SALS for providing quantitative analysis of effects of microgravity on structural and connective tissue.

  13. Reconstruction of three-dimensional anisotropic structure from small-angle scattering experiments

    NASA Astrophysics Data System (ADS)

    Huang, Guan-Rong; Wang, Yangyang; Wu, Bin; Wang, Zhe; Do, Changwoo; Smith, Gregory S.; Bras, Wim; Porcar, Lionel; Falus, Péter; Chen, Wei-Ren

    2017-08-01

    When subjected to flow, the structures of many soft-matter systems become anisotropic due to the symmetry breaking of the spatial arrangements of constituent particles at the microscopic level. At present, it is common practice to use various small-angle scattering techniques to explore flow-induced microstructural distortion. However, there has not been a thorough discussion in the literature on how a three-dimensional anisotropic structure can be faithfully reconstructed from two-dimensional small-angle scattering spectra. In this work, we address this issue rigorously from a mathematical perspective by using real spherical harmonic expansion analysis. We first show that, except for cases in which mechanical perturbation is sufficiently small, the existing small-angle scattering techniques generally do not provide complete information on structural distortion. This limitation is caused by the linear dependence of certain real spherical harmonic basis vectors on the flow-vorticity and flow-velocity gradient planes in the Couette shear cell. To circumvent the constraint imposed by this geometry, an alternative approach is proposed in which a parallel sliding plate shear cell is used with a central rotary axis along the flow direction. From the calculation of rotation of the reference frame, we demonstrate the feasibility of this experimental implementation for a fully resolved three-dimensional anisotropic structure via a case study of sheared polymers.

  14. Vortex lattice structure in BaFe2(As0.67P0.33)2 by the small-angle neutron scattering technique

    SciTech Connect

    Morisaki-Ishii, Rieko; Kawano-Furukawa, H.; Cameron, Alistair S.; Lemberger, L; Blackburn, Elizabeth; Holmes, Alexander T.; Forgan, E. M.; Debeer-Schmitt, Lisa M.; Littrell, Ken; Nakajima, M.; Kihou, K.; Lee, C. H.; Iyo, Akira; Eisaki, Hiroshi; Uchida, S.; White, Jonathon; Dewhurst, C. D.; Gavilano, Jorge; Zolliker, Marcus

    2014-09-09

    We have observed a magnetic vortex lattice (VL) inBaFe2(As0.67P0.33)2 single crystals by smallangle neutron scattering. With the field along the c-axis, a nearly isotropic hexagonal VL was formed in the field range from 1 to 16 T, and no symmetry changes in the VL were observed. The temperature-dependence of the VL signal was measured and confirms the presence of (non d-wave) nodes in the superconducting gap structure for measurements at 5 T and below. The nodal effects were suppressed at high fields. At low fields, a VL reorientation transition was observed between 1 T and 3 T, with the VL orientation changing by 45 . Below 1 T, the VL structure was strongly affected by pinning and the diffraction pattern had a fourfold symmetry. We suggest that this (and possibly also the VL reorientation) is due to pinning to defects aligned with the crystal structure, rather than being intrinsic. The temperature dependence of the scaled intensity suggest that BFAP possesses at least one full gap and one nodal gap with circular symmetry. Judging from the symmetry, the node structure should take the form of an accidental circular line node, which is consistent with recent ARPES results1.

  15. From Non-equilibrium to Equilibrium: Micellar Kinetics seen by Time-resolved Small-angle Scattering

    NASA Astrophysics Data System (ADS)

    Lund, Reidar

    The kinetic pathways of self-assembled nanostructures are not fully understood. Time-resolved small-angle X-ray/neutron scattering (TR-SAXS/SANS) is powerful technique1 that allows kinetics processes such as nucleation processes2,3 and morphological transitions4,5 to be followed with structural resolution over time scales starting from milliseconds. Neutrons offer the additional advantage of facile contrast variation through H/D substitution schemes, which also allow equilibrium processes such as molecular exchange and diffusion to be studied1 , 6 , 7. Here we will highlight the current capabilities of TR-SAS and show results on the kinetics of polymeric micelles. We will address how the understanding of kinetic pathways can be used control the nanostructure.

  16. Small angle X-ray scattering study of coal soot formation

    SciTech Connect

    Winans, R. E.; Parker, J. T.; Seifert, S.; Fletcher, T. H.

    2000-02-14

    The objective of this study is to examine, by small angle X-ray scattering (SAXS), the formation of soot from individual coal particle combustion in a methane flat flame burner. The SAXS instrument at the Basic Energy Sciences Synchrotron Radiation Center (BESSRC) at the Advanced Photon Source (APS) can be used to observe both the formation of spherules and clusters since it can access length scales of 6--6000 {angstrom}. The high X-ray flux enables rapid acquisition of scattering data of various regions of the flame. SAXS data reveal particle size, shape, surface areas, and surface roughness.

  17. Characterising density fluctuations in liquid yttria aluminates with small angle x-ray scattering

    SciTech Connect

    Greaves, G. Neville; Wilding, Martin C.; Vu Van, Quang; Majerus, Odile; Hennet, Louis

    2009-01-29

    Small angle x-ray scattering (SAXS) has been measured in the wavevector range 0.01scatter from longer range fluctuating volumes.

  18. MAGNETIC NEUTRON SCATTERING

    SciTech Connect

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    , ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.

  19. Structural characterization of chaos game fractals using small-angle scattering analysis.

    PubMed

    Anitas, Eugen Mircea; Slyamov, Azat

    2017-01-01

    Small-angle scattering (SAS) technique is applied to study the nano and microstructural properties of spatial patterns generated from chaos game representation (CGR). Using a simplified version of Debye formula, we calculate and analyze in momentum space, the monodisperse scattering structure factor from a system of randomly oriented and non-interacting 2D Sierpinski gaskets (SG). We show that within CGR approach, the main geometrical and fractal properties, such as the overall size, scaling factor, minimal distance between scattering units, fractal dimension and the number of units composing the SG, can be recovered. We confirm the numerical results, by developing a theoretical model which describes analytically the structure factor of SG. We apply our findings to scattering from single scale mass fractals, and respectively to a multiscale fractal representing DNA sequences, and for which an analytic description of the structure factor is not known a priori.

  20. Structural characterization of chaos game fractals using small-angle scattering analysis

    PubMed Central

    Slyamov, Azat

    2017-01-01

    Small-angle scattering (SAS) technique is applied to study the nano and microstructural properties of spatial patterns generated from chaos game representation (CGR). Using a simplified version of Debye formula, we calculate and analyze in momentum space, the monodisperse scattering structure factor from a system of randomly oriented and non-interacting 2D Sierpinski gaskets (SG). We show that within CGR approach, the main geometrical and fractal properties, such as the overall size, scaling factor, minimal distance between scattering units, fractal dimension and the number of units composing the SG, can be recovered. We confirm the numerical results, by developing a theoretical model which describes analytically the structure factor of SG. We apply our findings to scattering from single scale mass fractals, and respectively to a multiscale fractal representing DNA sequences, and for which an analytic description of the structure factor is not known a priori. PMID:28704515

  1. Characterization of Nanocomposite filler Morphology using Ultra Small-Angle X-ray Scattering

    SciTech Connect

    Justice, Ryan S.; Schaefer, Dale W.

    2010-10-22

    Loading polymer matrices with nanoscale fillers is widely believed to have the potential to push polymer properties to extreme values. Realization of anticipated properties, however, has proven elusive. Recent nanocomposite research suggests better characterization of the large-scale morphology will provide insight explaining these shortfalls. This work will present ultra-small angle X-ray scattering as a viable tool for elucidating the hierarchical filler morphology that exists within polymer nanocomposites. Scattering analysis tools developed by our group will be applied to scattering data from nanocomposites filled with carbon nanotubes, layered silicates, and colloidal silica. The relationship between imaging data and scattering data will be discussed in the context of filler dispersion. Finally, the impact of large-scale filler morphology on mechanical and electrical properties will be discussed.

  2. Global small-angle X-ray scattering data analysis for multilamellar vesicles: the evolution of the scattering density profile model

    PubMed Central

    Heftberger, Peter; Kollmitzer, Benjamin; Heberle, Frederick A.; Pan, Jianjun; Rappolt, Michael; Amenitsch, Heinz; Kučerka, Norbert; Katsaras, John; Pabst, Georg

    2014-01-01

    The highly successful scattering density profile (SDP) model, used to jointly analyze small-angle X-ray and neutron scattering data from unilamellar vesicles, has been adapted for use with data from fully hydrated, liquid crystalline multilamellar vesicles (MLVs). Using a genetic algorithm, this new method is capable of providing high-resolution structural information, as well as determining bilayer elastic bending fluctuations from standalone X-ray data. Structural parameters such as bilayer thickness and area per lipid were determined for a series of saturated and unsaturated lipids, as well as binary mixtures with cholesterol. The results are in good agreement with previously reported SDP data, which used both neutron and X-ray data. The inclusion of deuterated and non-deuterated MLV neutron data in the analysis improved the lipid backbone information but did not improve, within experimental error, the structural data regarding bilayer thickness and area per lipid. PMID:24587787

  3. Characterization of two new stable block copolymer mesophases by synchrotron small-angle scattering

    NASA Astrophysics Data System (ADS)

    Burger, C.; Micha, M. A.; Oestreich, S.; Förster, S.; Antonietti, M.

    1998-05-01

    Block copolymers made of polystyrene and fluorinated blocks represent a new class of polymers with a very strong incompatibility between the two blocks. They exhibit new stable block copolymer mesophases which are not considered in the phase diagrams of diblock copolymers in the strong and super-strong segregation regime. The solid-state structures of two polymers with different compositions are characterized by synchrotron small-angle X-ray scattering and transmission electron microscopy, thus proving the existence of a quadratically perforated layer phase and a 2D phase of sanidically degenerated cylinders.

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

    PubMed Central

    2012-01-01

    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. PMID:22800408

  5. Measurement of protein size in concentrated solutions by small angle X‐ray scattering

    PubMed Central

    Liu, Jun; Wei, Yanru; Wang, Wenjia; Wang, Bing; Liang, Hongli; Gao, Yuxi

    2016-01-01

    Abstract By simulations on the distance distribution function (DDF) derived from small angle X‐ray scattering (SAXS) theoretical data of a dense monodisperse system, we found a quantitative mathematical correlation between the apparent size of a spherically symmetric (or nearly spherically symmetric) homogenous particle and the concentration of the solution. SAXS experiments on protein solutions of human hemoglobin and horse myoglobin validated the correlation. This gives a new method to determine, from the SAXS DDF, the size of spherically symmetric (or nearly spherically symmetric) particles of a dense monodisperse system, specifically for protein solutions with interference effects. PMID:27241796

  6. Grazing exit small angle X-ray scattering on grain formation in polycrystalline metal films

    SciTech Connect

    Zhang, Wei; Robinson, Ian K.

    2009-09-25

    We recently proposed a new grazing exit geometry for measuring the small-angle scattering from thin film materials, which we call GESAXS, to contrast with the successful grazing incidence version, GISAXS. The technique is particularly useful for probing nanostructured thin film materials, especially when the coherence properties of the beam are employed. Here we demonstrate the application of GESAXS to evaporated metal films, prepared using an in-situ diffraction chamber, to investigate how their structure evolves upon annealing. Contrasting behavior is seen for Au, which preserves a roughly exponential distribution of domain sizes, and Fe for which the size distribution narrows by an Ostwald ripening process.

  7. Correlation between fractal dimension and surface characterization by small angle X-ray scattering in marble.

    PubMed

    Salinas-Nolasco, Manlio Favio; Méndez-Vivar, Juan

    2010-03-16

    Among several analysis techniques applied to the study of surface passivation using dicarboxylic acids, small angle X-ray scattering (SAXS) has proved to be relevant in the physicochemical interpretation of the surface association resulting between calcium carbonate and the molecular structure of malonic acid. It is possible to establish chemical affinity principles through bidimensional geometric analysis in terms of the fractal dimension obtained experimentally by SAXS. In this Article, we present results about the adsorption of malonic acid on calcite, using theoretical and mathematical principles of the fractal dimension.

  8. Small-angle X-ray scattering probe of intermolecular interaction in red blood cells

    NASA Astrophysics Data System (ADS)

    Liu, Guan-Fen; Wang, We-Jia; Xu, Jia-Hua; Dong, Yu-Hui

    2015-03-01

    With high concentrations of hemoglobin (Hb) in red blood cells, self-interactions among these molecules could increase the propensities of their polymerization and aggregation. In the present work, high concentration Hb in solution and red blood cells were analyzed by small-angle X-ray scattering. Calculation of the effective structure factor indicates that the interaction of Hb molecules is the same when they are crowded together in both the cell and physiological saline. The Hb molecules stay individual without the formation of aggregates and clusters in cells. Supported by National Basic Research Program of China (2009CB918600) and National Natural Science Foundation of China (10979005)

  9. SASfit: a tool for small-angle scattering data analysis using a library of analytical expressions

    PubMed Central

    Breßler, Ingo; Kohlbrecher, Joachim; Thünemann, Andreas F.

    2015-01-01

    SASfit is one of the mature programs for small-angle scattering data analysis and has been available for many years. This article describes the basic data processing and analysis workflow along with recent developments in the SASfit program package (version 0.94.6). They include (i) advanced algorithms for reduction of oversampled data sets, (ii) improved confidence assessment in the optimized model parameters and (iii) a flexible plug-in system for custom user-provided models. A scattering function of a mass fractal model of branched polymers in solution is provided as an example for implementing a plug-in. The new SASfit release is available for major platforms such as Windows, Linux and MacOS. To facilitate usage, it includes comprehensive indexed documentation as well as a web-based wiki for peer collaboration and online videos demonstrating basic usage. The use of SASfit is illustrated by interpretation of the small-angle X-ray scattering curves of monomodal gold nanoparticles (NIST reference material 8011) and bimodal silica nanoparticles (EU reference material ERM-FD-102). PMID:26500467

  10. Nucleon-nucleon scattering at small angles, measured at ANKE-COSY

    NASA Astrophysics Data System (ADS)

    Bagdasarian, Z.

    2016-03-01

    The most accepted approach to describe nucleon-nucleon (NN) interaction is the partial wave analysis (PWA), which translates various experimental observables to the common language of the partial waves. The reliable analysis relies not only on the quality experimental data, but also on the measurements of scattering observables over preferably the full angular range. Small angle scattering has been measured for six beam energies between 0.8 and 2.4 GeV using polarized proton beam incident on both proton and deuteron unpolarized targets at COSY-ANKE. This proceeding will report on the published and preliminary results for both pp and pn scattering from this and other recent experiments at ANKE. This study aims to provide the valuable observables to the SAID group in order to improve the phenomenological understanding of the nucleon-nucleon interaction.

  11. Anomalous small-angle x-ray scattering of a femtosecond irradiated germano silicate fibre preform.

    SciTech Connect

    Hindle, F.; Fertein, E.; Seifert, S.; Przygodski, C.S.; Bocquet, R.; Douay, M.; Bychkov, E.; Experimental Facilities Division; LPCA, CNRS; PhLAM; Univ. des Sciences et Tech. de Lille

    2005-01-01

    RADIATION is shown to induce significant mesoscopic structure. The scattering intensity for irradiated glasses is close to two orders of magnitude greater than that of unexposed material. Anomalous small-angle X-ray scattering (ASAXS) around the germanium K-edge for the silica and germanium doped silica regions of a fiber preform is used to demonstrate that identical structures are induced in both glass materials, with germanium displaying a capacity to isomorphically replace silicon in the case of the germanium doped silica. Analysis of measured scattering indicates that photo-inscribed features are produced at two distinct scales with typical radii of R {approx} 20 Angstroms and R{sub min} {approx} 200 Angstroms.

  12. A small-angle x-ray scattering system with a vertical layout

    SciTech Connect

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu; Cui, Kunpeng; Wu, Lihui; Li, Liangbin

    2014-12-15

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range. With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.

  13. Upgrade of small angle x-ray scattering beamline BL-6A at the photon factory

    SciTech Connect

    Takagi, H. Igarashi, N.; Mori, T.; Saijo, S.; Nagatani, Y.; Kosuge, T.; Shimizu, N.; Ohta, H.

    2016-07-27

    BL-6A has been operational since 2011 as a small angle X-ray scattering (SAXS) beamline at the Photon Factory (PF), and beginning in 2013 its old components and systems, which were mainly inside the experimental hutch, have been extensively updated. Both the vacuum-passes located between the sample stage and the detector and the fixed surface plate have been replaced by a new semi-automatic diffractometer. These upgrades allow simultaneous SAXS/WAXS experiments and grazing-incidence small angle X-ray scattering (GISAXS) measurements to be conducted. The hybrid pixel detector PILATUS3 1M is installed for SAXS, and PILATUS 100K is available as a WAXS detector. Additionally, a pinhole equipped with a micro-ion chamber is available to realize a lower-background and higher-resolution of low angles. Moreover, in a simultaneous SAXS/WAXS experiment, we developed a new beam stop with an embedded photodiode. Thus, BL-6A has evolved into a multipurpose beamline capable of dealing with various types of samples and experimental techniques.

  14. A small-angle x-ray scattering system with a vertical layout

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu; Cui, Kunpeng; Wu, Lihui; Li, Liangbin

    2014-12-01

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range. With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.

  15. A small-angle x-ray scattering system with a vertical layout.

    PubMed

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu; Cui, Kunpeng; Wu, Lihui; Li, Liangbin

    2014-12-01

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range. With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.

  16. Using Small-Angle Scattering Techniques to Understand Mechanical Properties of Biopolymer-Based Biomaterials

    PubMed Central

    Hyland, Laura L.; Taraban, Marc B.

    2013-01-01

    The design and engineering of innovative biopolymer-based biomaterials for a variety of biomedical applications should be based on the understanding of the relationship between their nanoscale structure and mechanical properties. Down the road, such understanding could be fundamental to tune the properties of engineered tissues, extracellular matrices for cell delivery and proliferation/differentiation, etc. In this tutorial review, we attempt to show in what way biomaterial structural data can help to understand the bulk material properties. We begin with some background on common types of biopolymers used in biomaterials research, discuss some typical mechanical testing techniques and then review how others in the field of biomaterials have utilized small-angle scattering for material characterization. Detailed examples are then used to show the full range of possible characterization techniques available for biopolymer-based biomaterials. Future developments in the area of material characterization by small-angle scattering will undoubtedly facilitate the use of structural data to control the kinetics of assembly and final properties of prospective biomaterials. PMID:24273590

  17. The structure of the muscle protein complex 4Ca{sup 2+}. Tronponin C*troponin: A Monte Carlo modeling analysis of small-angle X-ray and neutron scattering data

    SciTech Connect

    Olah, G.A.; Trewhella, J.

    1995-11-01

    Analysis of scattering data based on a Monte Carlo integration method was used to obtain a low resolution model of the 4Ca2+.troponin c.troponin I complex. This modeling method allows rapid testing of plausible structures where the best fit model can be ascertained by a comparison between model structure scattering profiles and measured scattering data. In the best fit model, troponin I appears as a spiral structure that wraps about 4CA2+.trophonin C which adopts an extended dumbell conformation similar to that observed in the crystal structures of troponin C. The Monte Carlo modeling method can be applied to other biological systems in which detailed structural information is lacking.

  18. Small-Angle X-Ray Scattering From RNA, Proteins, And Protein Complexes

    SciTech Connect

    Lipfert, Jan; Doniach, Sebastian; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /SLAC, SSRL

    2007-09-18

    Small-angle X-ray scattering (SAXS) is increasingly used to characterize the structure and interactions of biological macromolecules and their complexes in solution. Although still a low-resolution technique, the advent of high-flux synchrotron sources and the development of algorithms for the reconstruction of 3-D electron density maps from 1-D scattering profiles have made possible the generation of useful low-resolution molecular models from SAXS data. Furthermore, SAXS is well suited for the study of unfolded or partially folded conformational ensembles as a function of time or solution conditions. Here, we review recently developed algorithms for 3-D structure modeling and applications to protein complexes. Furthermore, we discuss the emerging use of SAXS as a tool to study membrane protein-detergent complexes. SAXS is proving useful to study the folding of functional RNA molecules, and finally we discuss uses of SAXS to study ensembles of denatured proteins.

  19. Quantitative evaluation of statistical errors in small-angle X-ray scattering measurements.

    PubMed

    Sedlak, Steffen M; Bruetzel, Linda K; Lipfert, Jan

    2017-04-01

    A new model is proposed for the measurement errors incurred in typical small-angle X-ray scattering (SAXS) experiments, which takes into account the setup geometry and physics of the measurement process. The model accurately captures the experimentally determined errors from a large range of synchrotron and in-house anode-based measurements. Its most general formulation gives for the variance of the buffer-subtracted SAXS intensity σ(2)(q) = [I(q) + const.]/(kq), where I(q) is the scattering intensity as a function of the momentum transfer q; k and const. are fitting parameters that are characteristic of the experimental setup. The model gives a concrete procedure for calculating realistic measurement errors for simulated SAXS profiles. In addition, the results provide guidelines for optimizing SAXS measurements, which are in line with established procedures for SAXS experiments, and enable a quantitative evaluation of measurement errors.

  20. Sample holder for small-angle x-ray scattering static and flow cell measurements

    SciTech Connect

    Lipfert, Jan; Millett, Ian S.; Seifert, Soenke; Doniach, Sebastian

    2006-04-15

    We present the design of a sample holder for small-angle x-ray scattering (SAXS) that can be used for both static and flow cell measurements, allowing to switch between these two types of measurement without having to realign the detector and camera geometry. The device makes possible high signal-to-noise experiments with sample volumes as small as 16 {mu}l and can be thermocontrolled using a standard circulating water bath. The setup has been used successfully for a range of biological SAXS measurements, including peptides, detergent micelles, membrane proteins, and nucleic acids. As a performance test, we present scattering data for horse heart cytochrome c, collected at the BESSRC CAT beam line 12-ID of the Advanced Photon Source. The design drawings are provided in the supplementary material.

  1. Quantitative evaluation of statistical errors in small-angle X-ray scattering measurements

    PubMed Central

    Sedlak, Steffen M.; Bruetzel, Linda K.; Lipfert, Jan

    2017-01-01

    A new model is proposed for the measurement errors incurred in typical small-angle X-ray scattering (SAXS) experiments, which takes into account the setup geometry and physics of the measurement process. The model accurately captures the experimentally determined errors from a large range of synchrotron and in-house anode-based measurements. Its most general formulation gives for the variance of the buffer-subtracted SAXS intensity σ2(q) = [I(q) + const.]/(kq), where I(q) is the scattering intensity as a function of the momentum transfer q; k and const. are fitting parameters that are characteristic of the experimental setup. The model gives a concrete procedure for calculating realistic measurement errors for simulated SAXS profiles. In addition, the results provide guidelines for optimizing SAXS measurements, which are in line with established procedures for SAXS experiments, and enable a quantitative evaluation of measurement errors. PMID:28381982

  2. Structural Analysis of the Flagellar Component Proteins in Solution by Small Angle X-Ray Scattering.

    PubMed

    Lee, Lawrence K

    2017-01-01

    Small angle X-ray scattering is an increasingly utilized method for characterizing the shape and structural properties of proteins in solution. The technique is amenable to very large protein complexes and to dynamic particles with different conformational states. It is therefore ideally suited to the analysis of some flagellar motor components. Indeed, we recently used the method to analyze the solution structure of the flagellar motor protein FliG, which when combined with high-resolution snapshots of conformational states from crystal structures, led to insights into conformational transitions that are important in mediating the self-assembly of the bacterial flagellar motor. Here, we describe procedures for X-ray scattering data collection of flagellar motor components, data analysis, and interpretation.

  3. Small angle light scattering characterization of single micrometric particles in microfluidic flows

    NASA Astrophysics Data System (ADS)

    Dannhauser, David; Romeo, Giovanni; Causa, Filippo; Netti, Paolo A.

    2013-04-01

    A CCD-camera based small angle light scattering (SALS) apparatus has been used to characterize single micrometric particles flowing in a micro-channel. The measured scattering vector spans the range 2x10-2 - 6:8x101μm-1. The incident laser light is collimated to a spot of about 50 μm in diameter at the sample position with a divergence lower than 0.045 rad. Such small collimated laser beam opens the possibility to perform on-line SALS of micron-sized particles flowing in micro-channels. By properly designing the micro-channel and using a viscoelastic liquid as suspending medium we are able to realize a precise 3D focusing of the target particles. The forward scattering emitted from the particle is collected by a lens with high numerical aperture. At the focal point of that lens a homemade beam stop is blocking the incident light. Finally, a second lens maps the scattered light on the CCD sensor, allowing to obtain far field images on short distances. Measurements with mono-disperse polystyrene particles, both in quiescent and in-flow conditions have been realized. Experiments in-flow allow to measure the single particle scattering. Results are validated by comparison with calculations based on the Lorenz-Mie theory. The quality of the measured intensity profiles confirms the possibility to use our apparatus in real multiplex applications, with particles down to 1 μm in radius.

  4. Depth profiling of polymer films with grazing-incidence small-angle X-ray scattering.

    PubMed

    Singh, Marsha A; Groves, Michael N

    2009-05-01

    A model-free method of reconstructing depth-specific lateral scattering from incident-angle-resolved grazing-incidence small-angle X-ray scattering (GISAXS) data is proposed. The information on the material which is available through variation of the X-ray penetration depth with incident angle is accessed through reference to the reflected branch of the GISAXS process. Reconstruction of the scattering from lateral density fluctuations is achieved by solving the resulting Fredholm integral equation with minimal a priori information about the experimental system. Results from simulated data generated for hypothetical multilayer polymer systems with constant absorption coefficient are used to verify that the method can be applied to cases with large X-ray penetration depths, as typically seen with polymer materials. Experimental tests on a spin-coated thick film of a blend of diblock copolymers demonstrate that the approach is capable of reconstruction of the scattering from a multilayer structure with the identification of lateral scattering profiles as a function of sample depth.

  5. Small angle x-ray scattering study of the porosity in coals

    NASA Astrophysics Data System (ADS)

    Schmidt, P. W.; Kalliat, M.; Kwak, C. Y.

    1981-02-01

    Small-angle scattering curves have bee obtained for some Pennsylvania State University PSOC coal samples and for several other coals. The x-ray scattering data provide information about the porosity in the coals and suggest that there are three classes of pores, which have average dimensions of the order of 1000 A˚, 30 A˚, and less than 5 A˚, corresponding to the macropores, transition pores and micropores discussed by Dubinin. The principal factor determining the form of the scattering curves has been found to be the rank of the coal. In coals of all ranks, the specific surface associated with the macropores is about 1 to 10 m2/gm. The micropores are most highly developed in high-rank coals. Comparison of the x-ray and adsorption results suggests that x-ray scattering and nitrogen adsorption detect only the specific surface of the macropores and transition pores, while carbon dioxide adsorption measures the total porosity from the micropores. Scattering data have also been recorded for a series of coals which had been tested for their suitability for conversion to liquid fuels. All the coals which were well-suited for producing liquid fuels were found to have a well-developed transition pore structure, while coals which were not especially good for coal liquefaction processes had almost no transition pores.

  6. Small-angle x-ray scattering studies of the manganese stabilizing subunit in photosystem II.

    SciTech Connect

    Svensson, B.; Tiede, D. M.; Barry, B. A.; Univ. of Minnesota

    2002-08-29

    Small-angle X-ray scattering studies (SAXS) were used to determine the size, shape, and oligomeric composition of the manganese stabilizing protein (MSP) of photosystem II. This extrinsic protein subunit plays an important role in photosynthetic oxygen evolution. As its name implies, MSP stabilizes the tetranuclear Mn cluster of the water oxidation complex. Removal of MSP lowers activity and decreases the stability of active-site manganese. Reconstitution of MSP reverses these effects. In this study, MSP was extracted from spinach PSII membranes using CaCl{sub 2} or urea. Through the use of MALDI-TOF mass spectrometry, the molecular weight of MSP was determined to be 26.53 kDa. X-ray scattering results show that both samples display a monodisperse scattering pattern; this pattern is consistent with a homogeneous protein solution. The CaCl{sub 2} extracted and urea extracted MSP samples have radii of gyration of 25.9 {+-} 0.4 and 27.0 {+-} 0.01 {angstrom}, respectively. MSP is shown to be monomeric in solution. This was determined using a cytochrome c standard and the scattering intensity, extrapolated to zero scattering angle, which is proportional to the molecular weight. This SAXS study suggests that, in solution, MSP is a monomeric, elongated prolate ellipsoid with dimensions, 112 x 23 x 23 {angstrom}{sup 3} and an axial ratio of 4.8.

  7. A Laboratory Scale Critical-Dimension Small-Angle X-ray Scattering Instrument

    SciTech Connect

    Ho, Derek L.; Wang Chengqing; Lin, Eric K.; Jones, Ronald L.; Wu Wenli

    2007-09-26

    New methods for critical dimension (CD) measurements may be needed to enable the detailed characterization of nanoscale structures produced in the semiconductor industry and for nanotechnology applications. In earlier work, small angle x-ray scattering (SAXS) measurements with synchrotron sources have shown promise in meeting several grand challenges for CD metrology. However, it is not practical to depend upon x-ray synchrotron sources, which are large national facilities with limitations in the number of available instruments. To address this problem, a laboratory scale SAXS instrument for critical dimension measurements on periodic nanoscale patterns has been designed, installed, and tested. The system possesses two configurations, SAXS and ultra-small-angle x-ray scattering (USAXS), with a radiation target of either copper or molybdenum. With these configurations, the instrument is capable of accessing scattering angles that probe length scales ranging from ca. 0.5 nm to 2 {mu}m. In this work, we compare CD-SAXS measurements taken from a synchrotron-based SAXS at the Advanced Photon Source of the Argonne National Laboratory with those from the National Institute of Standards and Technology laboratory-scale SAXS instrument. The results from standard line/space gratings possessing periodic line-space patterns with CDs of tens to hundreds of nanometers show that the laboratory-scale system can quantitatively measure parameters, such as the pitch, line width, height, line-width roughness and sidewall angle. These results show that laboratory-scale measurements are feasible and can be used for research and development purposes or to assist calibration of optical scatterometry and CD-scanning electron microscopy instruments. The primary limitation of the measurement is that the data collection rate is unacceptably slow for production metrology because of the significantly lower x-ray beam fluxes currently available.

  8. Analytical model for determination of parameters of helical structures in solution by small angle scattering: comparison of RecA structures by SANS.

    PubMed

    Lebedev, D V; Baitin, D M; Islamov, A Kh; Kuklin, A I; Shalguev, V Kh; Lanzov, V A; Isaev-Ivanov, V V

    2003-02-27

    The filament structures of the self-polymers of RecA proteins from Escherichia coli and Pseudomonas aeruginosa, their complexes with ATPgammaS, phage M13 single-stranded DNA (ssDNA) and the tertiary complexes RecA::ATPgammaS::ssDNA were compared by small angle neutron scattering. A model was developed that allowed for an analytical solution for small angle scattering on a long helical filament, making it possible to obtain the helical pitch and the mean diameter of the protein filament from the scattering curves. The results suggest that the structure of the filaments formed by these two RecA proteins, and particularly their complexes with ATPgammaS, is conservative.

  9. A Microbeam Small-Angle X-ray Scattering Study on Enamel Crystallites in Subsurface Lesion

    NASA Astrophysics Data System (ADS)

    Yagi, N.; Ohta, N.; Matsuo, T.; Tanaka, T.; Terada, Y.; Kamasaka, H.; Kometani, T.

    2010-10-01

    The early caries lesion in bovine tooth enamel was studied by two different X-ray diffraction systems at the SPring-8 third generation synchrotron radiation facility. Both allowed us simultaneous measurement of the small and large angle regions. The beam size was 6μm at BL40XU and 50μm at BL45XU. The small-angle scattering from voids in the hydroxyapatite crystallites and the wide-angle diffraction from the hydroxyapatite crystals were observed simultaneously. At BL40XU an X-ray image intensifier was used for the small-angle and a CMOS flatpanel detector for the large-angle region. At BL45XU, a large-area CCD detector was used to cover both regions. A linear microbeam scan at BL40XU showed a detailed distribution of voids and crystals and made it possible to examine the structural details in the lesion. The