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Sample records for angle scattering techniques

  1. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    SciTech Connect

    Meyer, Matthew W.

    2013-01-01

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  2. 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)

  3. Sample environments and techniques combined with small angle X-ray scattering.

    PubMed

    Bras, W; Ryan, A J

    1998-03-31

    The number of synchrotron radiation-based Small Angle X-ray Scattering beamlines has increased considerably over the last decade. With the high X-ray flux and collimation of these beamlines it not only has become possible to perform time-resolved experiments on time scales down to the millisecond/frame range, but also it allows experimenters to utilise new sample environments and use simultaneous several experimental techniques on one sample. An overview of recent developments in this field is given.

  4. Quantification of microstructural features in HMX using small angle neutron scattering techniques

    SciTech Connect

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

    1998-12-01

    Microstructural features in raw powders of High Explosives have been qualitatively observed by many researchers, using polarized light and scanning electron microscopy. Here, the authors present a method for non-destructive quantification of volume fraction and structure of intragranular cracks and crystallization voids in a bulk sample (100--300 mg). By employing Small Angle Neutron Scattering (SANS) in conjunction with the method of contrast variation, they can effectively highlight different structural features of a complex system. The technique of contrast variation relies on immersing the sample in a uniform fluid of known neutron scattering length density. By selectively varying the scattering length density of the immersion fluid, scattering contributions from internal and external structures can be separated. This approach is analogous to varying the index of refraction for immersion oil relative to a sample in polarized light microscopy. SANS experiments on HMX were conducted using loose powders (261 and 10 micron mean particle diameters) and pellets made by uniaxial consolidation (without binder) to 7 and 10 volume percent porosity respectively. Detailed modeling of the SANS data indicate significant alteration of the intragranular void/crack/pore structure, with pressing, of the HMX powders.

  5. 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

  6. 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.

  7. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments

    PubMed Central

    Bras, Wim; Koizumi, Satoshi; Terrill, Nicholas J

    2014-01-01

    Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments. PMID:25485128

  8. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments.

    PubMed

    Bras, Wim; Koizumi, Satoshi; Terrill, Nicholas J

    2014-11-01

    Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

  9. Angle resolved scatter measurement of bulk scattering in transparent ceramics

    NASA Astrophysics Data System (ADS)

    Sharma, Saurabh; Miller, J. Keith; Shori, Ramesh K.; Goorsky, Mark S.

    2015-02-01

    Bulk scattering in polycrystalline laser materials (PLM), due to non-uniform refractive index across the bulk, is regarded as the primary loss mechanism leading to degradation of laser performance with higher threshold and lower output power. The need for characterization techniques towards identifying bulk scatter and assessing the quality. Assessment of optical quality and the identification of bulk scatter have been by simple visual inspection of thin samples of PLMs, thus making the measurements highly subjective and inaccurate. Angle Resolved Scatter (ARS) measurement allows for the spatial mapping of scattered light at all possible angles about a sample, mapping the intensity for both forward scatter and back-scatter regions. The cumulative scattered light intensity, in the forward scatter direction, away from the specular beam is used for the comparison of bulk scattering between samples. This technique employ the detection of scattered light at all angles away from the specular beam directions and represented as a 2-D polar map. The high sensitivity of the ARS technique allows us to compare bulk scattering in different PLM samples which otherwise had similar transmitted beam wavefront distortions.

  10. Neutron spin echo scattering angle measurement (SESAME)

    SciTech Connect

    Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

    2005-05-15

    We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-{mu}m-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for.

  11. 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.

  12. 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.

  13. Solutions for implementing time-of-flight techniques in low-angle neutron scattering, as realized on the Low-Q Diffractometer at Los Alamos

    SciTech Connect

    Hjelm, R.P. Jr.; Seeger, P.A.

    1992-12-01

    The implementation of small-angle (Low-momentum transfer) neutron scattering at pulsed spallation sources, using time of flight methods, has meant the introduction of some new ideas in instrument design, data acquisition, data reduction and computer management of the experiment and the data. Here we recount some of the salient aspects of solutions for implementing time of fight small-angle neutron scattering instruments at pulsed sources, as realized on the Low-Q Diffractometer, LQD, at Los Alamos. We consider, fortlier, some of the problems that are yet to be solved, and take a short excursion into the future of SANS instrumentation at pulsed sources.

  14. Solutions for implementing time-of-flight techniques in low-angle neutron scattering, as realized on the Low-Q Diffractometer at Los Alamos

    SciTech Connect

    Hjelm, R.P. Jr.; Seeger, P.A.

    1992-01-01

    The implementation of small-angle (Low-momentum transfer) neutron scattering at pulsed spallation sources, using time of flight methods, has meant the introduction of some new ideas in instrument design, data acquisition, data reduction and computer management of the experiment and the data. Here we recount some of the salient aspects of solutions for implementing time of fight small-angle neutron scattering instruments at pulsed sources, as realized on the Low-Q Diffractometer, LQD, at Los Alamos. We consider, fortlier, some of the problems that are yet to be solved, and take a short excursion into the future of SANS instrumentation at pulsed sources.

  15. 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.

  16. Application of the small-angle neutron scattering technique to the study of solubilization mechanisms of organic molecules by micellar systems

    NASA Astrophysics Data System (ADS)

    Caponetti, E.; Martino, D. Chillura; Floriano, M. A.; Triolo, R.

    1996-09-01

    We present the possible contribution of the small-angle neutron scattering (SANS) technique to the molecular interpretation of the solubilization phenomena in simple micellar systems. We show for a few ternary micellar systems, that an appropriate analysis of SANS experimental data can provide information on modifications induced on micellar dimension, shape, number of monomer, and charge and on the partition coefficient of the additive and its localization inside the micellar aggregate. The influence of n-alcohols on the thermodynamics and on the structure of sodium dodecyl sulphate (SDS) aqueous solution has been extensively investigated, so the agreement between the results obtained in previous work and those obtained in this study allows the validity of data analysis procedure to be verified. The study of SDS and dodecyltrimethylammonium bromide (DTAB) solutions, containing alternatively five different macrocycles showed that: in the case of SDS solution different, but in all cases appreciable, amounts of solute were found to be localized in the micellar phase, while for most DTAB solutions there was evidence for their localization in the aqueous phase. By analysing the single system, it was not possible to establish whether the solute was in the "core" or in the "shell" of the aggregate, but from a comparison between the results related to the two surfactant systems and from the different molecular properties of the macrocycles it was possible to localize each of them inside the aggregate and to explain the different amounts found.

  17. A more informative approach for characterization of polymer monolithic phases: small angle neutron scattering/ultrasmall angle neutron scattering.

    PubMed

    Ford, Kathleen M; Konzman, Brian G; Rubinson, Judith F

    2011-12-15

    Neutron scattering techniques have been used frequently to characterize geological specimens and to determine the structures of glasses and of polymers as solutions, suspensions, or melts. Little work has been reported on their application in determining polymers' structural properties relevant to separations. Here, we present a comparison of characterization results from nitrogen porosimetry and from combined small angle neutron scattering (SANS) and ultrasmall angle neutron scattering (USANS) experiments. We show that SANS is extremely sensitive to the pore characteristics. Both approaches can provide information about porosity and pore characteristics, but the neutron scattering techniques provide additional information in the form of the surface characteristics of the pores and their length scales. Fits of the scattering data show that cylindrical pores are present with diameters down to 0.6 μm and that, for length scales down to approxmately 20 Å, the material shows self-similar (fractal) slopes of -3.4 to -3.6. Comparison of these characteristics with other examples from the scattering literature indicate that further investigation of their meaning for chromatographic media is required. PMID:22066706

  18. Small-angle scattering from fat fractals

    NASA Astrophysics Data System (ADS)

    Anitas, Eugen M.

    2014-06-01

    A number of experimental small-angle scattering (SAS) data are characterized by a succession of power-law decays with arbitrarily decreasing values of scattering exponents. To describe such data, here we develop a new theoretical model based on 3D fat fractals (sets with fractal structure, but nonzero volume) and show how one can extract structural information about the underlying fractal structure. We calculate analytically the monodisperse and polydisperse SAS intensity (fractal form factor and structure factor) of a newly introduced model of fat fractals and study its properties in momentum space. The system is a 3D deterministic mass fractal built on an extension of the well-known Cantor fractal. The model allows us to explain a succession of power-law decays and respectively, of generalized power-law decays (GPLD; superposition of maxima and minima on a power-law decay) with arbitrarily decreasing scattering exponents in the range from zero to three. We show that within the model, the present analysis allows us to obtain the edges of all the fractal regions in the momentum space, the number of fractal iteration and the fractal dimensions and scaling factors at each structural level in the fractal. We applied our model to calculate an analytical expression for the radius of gyration of the fractal. The obtained quantities characterizing the fat fractal are correlated to variation of scaling factor with the iteration number.

  19. 12C(p,p‧) scattering measurement at forward angles

    NASA Astrophysics Data System (ADS)

    Tamii, A.; Adachi, T.; Fujita, K.; Hatanaka, K.; Hashimoto, H.; Itoh, M.; Matsubara, H.; Nakanishi, K.; Sakemi, Y.; Shimbara, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Fujita, Y.; Sakaguchi, H.; Zenihiro, J.; Kawabata, T.; Sasamoto, Y.; Dozono, M.; Carter, J.; Fujita, H.; Rubio, B.; Perez, A.

    Experimental method of measuring inelastic proton scattering with high-resolution at forward angles including zero degrees has been developed. An energy resolution of 20 keV and a scattering angle resolution of 0.5 degrees have been achieved as well as low background condition and a reliable background subtraction method. The experimental technique was applied to the 12C(p,p‧) reaction for studying the property of the second 0+ state at 7.7 MeV and a broad bump around Ex~10 MeV, where the presence of a 2+ state was reported from the 12C(α,α‧) measurement. Preliminary spectra and angular distributions are shown.

  20. Investigating hard sphere interactions through spin echo scattering angle measurement

    NASA Astrophysics Data System (ADS)

    Washington, Adam

    Spin Echo Scattering Angle Measurement (SESAME) allows neutron scattering instruments to perform real space measurements on large micron scale samples by encoding the scattering angle into the neutron's spin state via Larmor precession. I have built a SESAME instrument at the Low Energy Neutron Source. I have also assisted in the construction of a modular SESAME instrument on the ASTERIX beamline at Los Alamos National lab. The ability to tune these instruments has been proved mathematically and optimized and automated experimentally. Practical limits of the SESAME technique with respect to polarization analyzers, neutron spectra, Larmor elements, and data analysis were investigated. The SESAME technique was used to examine the interaction of hard spheres under depletion. Poly(methyl methacrylate) spheres suspended in decalin had previously been studied as a hard sphere solution. The interparticle correlations between the spheres were found to match the Percus-Yevick closure, as had been previously seen in dynamical light scattering experiments. To expand beyond pure hard spheres, 900kDa polystyrene was added to the solution in concentrations of less than 1% by mass. The steric effects of the polystyrene were expected to produce a short-range, attractive, "sticky" potential. Experiment showed, however, that the "sticky" potential was not a stable state and that the spheres would eventually form long range aggregates.

  1. Low-angle X-ray scattering from spices

    NASA Astrophysics Data System (ADS)

    Desouky, Omar S.; Ashour, Ahmed H.; Abdullah, Mohamed I.; Elshemey, Wael M.

    2002-07-01

    Low-angle scattering of X-rays is characterized by the presence of one or more peaks in the forward direction of scattering. These peaks are due to the interference of photons coherently scattered from the molecules of the medium. Thus these patterns are closely linked to the molecular structure of the investigated medium. In this work, low-angle X-ray scattering (LAXS) profiles of five spices; pimpinella anisum (anise), coriandrum sativum (coriander), cuminum cyminum (cumin), foenculum vulgare (fennel) and nigella sativa (nigella or black cumin) are presented after extensive measurements. It is found that all spices exhibit one characteristic peak at a scattering angle around 10°. This is equivalent to a value x=0.0565 Å -1, where x=sin( θ⧸2)⧸ λ. The full width at half maximum (FWHM) of this peak is found to be characteristic for each type of the investigated spices. The possibility to detect the irradiation of these spices from their LAXS profiles is also examined after 10, 20, 30 and 40 kGy doses of gamma radiation. Except for anise, coriander and cumin at 40 kGy, there are no detectable deviations from the control samples in the scattering profiles of irradiated samples. These results comply with the recommendations of the FDA (US Food and Drug Administration) which defines 30 kGy as the maximum dose for irradiation of spices. The present technique could be used to detect over-irradiation, which causes damage to the molecular structure of some spices.

  2. 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.

  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. Coincidence measurements of electron-impact coherence parameters for e-He scattering in the full range of scattering angles

    SciTech Connect

    Klosowski, Lukasz; Piwinski, Mariusz; Dziczek, Dariusz; Pleskacz, Katarzyna; Chwirot, Stanislaw

    2009-12-15

    Electron impact coherence parameters for inelastic e-He scattering have been measured for the excitation to the 2 {sup 1}P{sub 1} state at collision energy of 100 eV. The experiment was conducted using angular correlation electron-photon coincidence technique with a magnetic angle changer allowing measurements in full range of scattering angles. The results are compared with other experimental data and theoretical predictions available for this collisional system.

  5. Multiangle static and dynamic light scattering in the intermediate scattering angle range

    NASA Astrophysics Data System (ADS)

    Tamborini, E.; Cipelletti, L.

    2012-09-01

    We describe a light scattering apparatus based on a novel optical scheme covering the scattering angle range 0.5° ⩽ θ ⩽ 25°, an intermediate regime at the frontier between wide angle and small angle setups that is difficult to access by existing instruments. Our apparatus uses standard, readily available optomechanical components. Thanks to the use of a charge-coupled device detector, both static and dynamic light scattering can be performed simultaneously at several scattering angles. We demonstrate the capabilities of our apparatus by measuring the scattering profile of a variety of samples and the Brownian dynamics of a dilute colloidal suspension.

  6. Multiangle static and dynamic light scattering in the intermediate scattering angle range.

    PubMed

    Tamborini, E; Cipelletti, L

    2012-09-01

    We describe a light scattering apparatus based on a novel optical scheme covering the scattering angle range 0.5° ≤ θ ≤ 25°, an intermediate regime at the frontier between wide angle and small angle setups that is difficult to access by existing instruments. Our apparatus uses standard, readily available optomechanical components. Thanks to the use of a charge-coupled device detector, both static and dynamic light scattering can be performed simultaneously at several scattering angles. We demonstrate the capabilities of our apparatus by measuring the scattering profile of a variety of samples and the Brownian dynamics of a dilute colloidal suspension. PMID:23020361

  7. Crystal structure analysis in solution-processed uniaxially oriented polycrystalline thin film of non-peripheral octahexyl phthalocyanine by grazing incidence wide-angle x-ray scattering techniques

    NASA Astrophysics Data System (ADS)

    Ohmori, Masashi; Uno, Takashi; Nakatani, Mitsuhiro; Nakano, Chika; Fujii, Akihiko; Ozaki, Masanori

    2016-10-01

    Uniaxially oriented thin films of metal-free non-peripherally octahexyl-substituted phthalocyanine (C6PcH2), which exhibits high carrier mobility, have been fabricated by the bar-coating technique, which is a simple solution process. The molecular orientation and molecular steps in the thin film were observed by the polarized spectroscopy and the atomic force microscopy, respectively. The three-dimensional molecular packing structure in the thin film was investigated by the grazing incidence wide-angle X-ray scattering technique with an in-plane sample rotation. The crystal orientation was clarified, and the three-dimensional molecular packing structure of the thin film was found to match the single crystal structure. Moreover, the X-ray diffraction patterns of the oriented thin films were simulated by using the lattice parameters of C6PcH2 single crystal to reproduce the observed X-ray diffraction patterns.

  8. 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.

  9. 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; 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 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

  10. Small angle neutron scattering from nanometer grain sized materials

    SciTech Connect

    Epperson, J.E.; Siegel, R.W.

    1991-11-01

    Small angie neutron scattering has been utilized, along with a number of complementary characterization methods suitable to the nanometer size scale, to investigate the structures of cluster-assembled nanophase materials. Results of these investigations are described and problems and opportunities in using small angle scattering for elucidating nanostructures are discussed.

  11. Precision Determination of Electron Scattering Angle by Differential Nuclear Recoil Energy Method

    SciTech Connect

    Liyanage, Nilanga; Saenboonruang, Kiadtisak

    2015-09-01

    The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of the electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.

  12. Precision determination of electron scattering angle by differential nuclear recoil energy method

    SciTech Connect

    Liyanage, N.; Saenboonruang, K.

    2015-12-01

    The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of the electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.

  13. Soller collimators for small angle neutron scattering

    SciTech Connect

    Crawford, R.K.; Epperson, J.E.; Thiyagarajan, P.

    1988-09-30

    Small angle diffractometers at pulsed sources need to have fairly short flight paths if they are to make use of the long-wavelength portion of the spectrum without encountering problems from frame overlap or sacrificing intensity with band-limiting or pulse-removing choppers. With such short flight paths, achieving the necessary angular collimation in the incident beam while utilizing the full source size (/approximately/10 cm diameter) and a reasonable sample size (/approximately/1 cm diameter) requires the use of converging multiple-aperture collimation. If the collimation channels are all focused to the same point on the detector then the large sample size will not affect Q/sub min/ or the Q-resolution, even if the sample-to-detector distance is short. The Small Angle Diffractometer (SAD) at IPNS uses crossed converging soller collimators to provide focusing multiple-aperture collimation having /approximately/400 converging beam channels with essentially no ''dead'' space between them. This entire collimator system occupies a distance of only /approximately/60 cm along the incident flight path, while providing angular collimation of 0.003 radians FWHM. The dimensions for the SAD upstream collimator are L/sub c/ = 32.8 cm, d/sub 1/ = 0.974 mm, d/sub 2/ = 0.851 mm, while for the SAD downstream collimator L/sub c/ = 25.0 cm, d/sub 1/ - 0.844 mm, d/sub 2/ = 0.750 mm. Each of these collimators has 20 blades defining 21 horizontal or vertical channels. 4 refs., 6 figs.

  14. Characterisation of porous materials by combining mercury porosimetry and scattering techniques

    NASA Astrophysics Data System (ADS)

    Stefanopoulos, K. L.; Steriotis, Th. A.; Mitropoulos, A. Ch.; Kanellopoulos, N. K.; Treimer, W.

    2004-07-01

    Small-angle neutron scattering (SANS), ultra small-angle neutron scattering (USANS) and mercury porosimetry have been used to fully characterise macroporous chalk as well as Si3N4 and BaTiO3 samples. For the scattering techniques, multiple scattering effects have been studied. In addition, the scattering data have been evaluated by using a generalised form of the indirect Fourier transformation technique suitable for concentrated systems. Pore size distributions are calculated and compared to the mercury porosimetry results.

  15. Practical applications of small-angle neutron scattering.

    PubMed

    Hollamby, Martin J

    2013-07-14

    Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel. Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below. PMID:23552189

  16. Practical applications of small-angle neutron scattering.

    PubMed

    Hollamby, Martin J

    2013-07-14

    Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel. Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below.

  17. 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

  18. 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.

  19. Losses of ring current ions by strong pitch angle scattering

    NASA Astrophysics Data System (ADS)

    Walt, M.; Voss, H. D.

    High angular resolution measurements of 155 keV ions in the ring current during the magnetic storm of August 6, 1998 show filled loss cones indicating that very rapid pitch angle scattering is taking place above the satellite location. The measurements were made with the SEPS detector on the Polar satellite during its passages through the ring current regions, usually at magnetic latitudes near ±45° and at magnetic local times of about 04:00 and 16:00 hrs. The observed strong pitch angle scattering implies a trapping lifetime of less than an hour and may explain the early rapid recovery of Dst during magnetic storms.

  20. Pitch angle scattering of energetic particles by oblique whistler waves

    NASA Technical Reports Server (NTRS)

    Inan, U. S.; Bell, T. F.

    1991-01-01

    First order cyclotron or Landau resonant pitch angle scattering of electrons by oblique whistler waves propagating at large angles to the ambient field are found to be at least as large as that due to parallel propagating waves. Commonly observed precipitation of more than 40 keV electrons in association with ducted whistlers may thus be accompanied by substantial fluxes of lower energy (10 eV-40 keV) electrons precipitated by the nonducted components.

  1. Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

    PubMed Central

    Jo, YoungJu; Jung, JaeHwang; Lee, Jee Woong; Shin, Della; Park, HyunJoo; Nam, Ki Tae; Park, Ji-Ho; Park, YongKeun

    2014-01-01

    Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from −70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth. PMID:24867385

  2. Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

    NASA Astrophysics Data System (ADS)

    Jo, Youngju; Jung, Jaehwang; Lee, Jee Woong; Shin, Della; Park, Hyunjoo; Nam, Ki Tae; Park, Ji-Ho; Park, Yongkeun

    2014-05-01

    Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from -70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth.

  3. Parity Violation in Forward Angle Elastic Electron Proton Scattering

    SciTech Connect

    Krishna Kumar

    1999-07-01

    HAPPEX is a new experiment to probe the strange structure of the nucleon with parity violating electron scattering. We describe the physics motivation, provide an experimental overview and report on the results from the first data run. The asymmetry for the elastic scattering of 3.3 GeV electrons off target protons at a scattering angle of 12.5 degrees was measured to a precision of 15% of itself. The contribution from strange quark form factors was found to be zero within the experimental and theoretical uncertainties.

  4. Near-critical-angle scattering for the characterization of clouds of bubbles: particular effects.

    PubMed

    Onofri, Fabrice R A; Krzysiek, Mariusz A; Barbosa, Séverine; Messager, Valérie; Ren, Kuan-Fang; Mroczka, Janusz

    2011-10-20

    We report experimental investigations on the influence of various optical effects on the far-field scattering pattern produced by a cloud of optical bubbles near the critical scattering angle. Among the effects considered, there is the change of the relative refractive index of the bubbles (gas bubbles or some liquid-liquid droplets), the influence of intensity gradients induced by the laser beam intensity profile and by the spatial filtering of the collection optics, the coherent and multiple scattering effects occurring for densely packed bubbles, and the tilt angle of spheroidal optical bubbles. The results obtained herein are thought to be fundamental for the development of future works to model these effects and for the extension of the range of applicability of an inverse technique (referenced herein as the critical angle refractometry and sizing technique), which is used to determine the size distribution and composition of bubbly flows.

  5. Ultra Small-Angle Neutron Scattering Study of Porous Glass

    SciTech Connect

    Desai, Reshma R.; Desa, J. A. Erwin; Sen, D.; Mazumder, S.

    2011-07-15

    Compacts of silica micro-spheres prepared for different times at sintering temperatures of 640 deg. C and 740 deg. C have been studied by Ultra Small-Angle Neutron Scattering (USANS) and Scanning Electron Microscopy (SEM). Stress versus strain measurements display several breakage points related to a range of nearest neighbour coordination around each microsphere.

  6. Computational analysis of mitochondrial placement and aggregation effects on wide-angle cell scattering patterns

    NASA Astrophysics Data System (ADS)

    Pilarski, Patrick M.; Su, Xuan-Tao; Glerum, D. Moira; Backhouse, Christopher J.

    2009-02-01

    Image analysis and pattern recognition are key elements of many biomedical analysis schemes. In this work, we show the use of pattern recognition and classification for the study of an interesting biomedical problem- the prediction of organelle arrangement within a cell based on wide-angle light scattering patterns. Organelle distribution is known to relate to disease and drug resistance. However, up until this point it has been unclear how changes to organelle distribution relate to the composition of wide-angle light scattering patterns. As such, we use a rapid new scattering simulation method and standard pattern analysis techniques to demonstrate clear correlations between scattering pattern composition and organelle distribution. The texture of scattering images-specifically the spot and edge content of samples is found to directly relate to the type and size of organelle distributions within a cell. These relationships are used to quickly classify organelle distributions to a high degree of accuracy.

  7. Pitch-angle scattering of cometary ions: Computer simulations

    SciTech Connect

    Gary, S.P.; Winske, D. ); Miller, R.H. )

    1991-06-01

    Pitch-angle evolution of newborn cometary ion is studied by means of one-dimensional electromagnetic hybrid computer simulations of homogeneous plasmas. Newborn ions are injected into the simulations at a constant rate, with a velocity relative to the solar wind which makes an angle {alpha} with respect to the ambient magnetic field. The simulations are done with relatively weak ion injection rates commensurate with those in the distant environment of comet Halley. In response to the linear temporal growth of the fluctuating magnetic field energy, the injected ions pitch-angle scatter toward isotropy in both the quasi-parallel (0{degree} {le} {alpha} {approx} {le} 60{degree}) and quasi-perpendicular(60{degree} < {alpha} {le} 90{degree}) regimes. For the injection of cometary oxygen ions the simulations show pitch angle scattering rates that are essentially independent of the solar wind ion/cometary ion relative speed, and increase as the square root of the injection rate. Furthermore, the oxygen ion pitch angle scattering rate at perpendicular injection is approximately twice that in the quasi-parallel regime, in qualitative agreement with observations at comet Halley.

  8. 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.

  9. 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

  10. 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.

  11. 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

    2016-01-01

    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

  12. Physical characteristics of human transferrin from small angle neutron scattering.

    PubMed Central

    Martel, P; Kim, S M; Powell, B M

    1980-01-01

    The technique of small angle neutron scattering has been used to determine the molecular shape, the volume, and the molecular weight of pooled human transferrin in an aqueous solution isotonic with blood. Analysis of the measurements assuming a spheroidal molecular shape indicates that an oblate spheroid with semi-axes of length 46.6 +/- 1.4, 46.6 +/- 1.4 and 15.8 +/- 3.8 A, and a molecular volume of (144 +/- 45) X 10(3) A3 is the best simple approximation to the shape of the transferrin molecule. The radius of gyration, Rg, determined from a Guinier plot is 30.25 +/- 0.49 A, in agreement with Rg calculated for the oblate spheroidal shape. The molecular weight is determined to be (75 +/- 5) X 10(3). The shape-independent molecular volume is found to be (98 +/- 10) X 10(3) A3. The difference in the two volumes suggests that transferrin is not a uniform spheroid but may have a more complex shape. PMID:7260293

  13. Small-Angle Neutron Scattering Studies of a-Si:H and a-Si:D

    SciTech Connect

    Williamson, D. L.; Marr, D. W. M.; Nelson, B. P.; Iwaniczko, E.; Yang, J.; Yan, B.; Guha, S.

    2000-01-01

    The heterogeneity of hydrogen and deuterium on the nanometer scale has been probed by samll-angle neutron scattering (SANS) from a-Si:H and a-Si:D films. Films were depsoited by two techniques, plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) using conditions that yield high quality films and devices.

  14. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

    2016-10-01

    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  15. Study of M1 and E1 excitations by high-resolution proton inelastic scattering measurement at forward angles

    SciTech Connect

    Tamii, A.; Adachi, T.; Hatanaka, K.; Hashimoto, H.; Kaneda, T.; Matsubara, H.; Okamura, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Carter, J.; Dozono, M.; Fujita, H.; Fujita, Y.; Itoh, M.; Kawabata, T.; Nakanishi, K.; Sasamoto, Y.; Neumann-Cosel, P. von

    2007-06-13

    Experimental technique for measuring proton inelastic scattering with high-resolution at 295 MeV and at forward angles including zero degrees is described. The method is useful for extracting spin part of the M1 strength via nuclear excitation as well as E1 strength via Coulomb excitation. An excitation energy resolution of 20 keV, good scattering angle resolution, and low background condition have been achieved. The experimental technique was applied for several sd and pf shell nuclei.

  16. Ring Current Ion Losses by Pitch Angle Scattering

    NASA Astrophysics Data System (ADS)

    Walt, M.; Voss, H. D.

    2001-12-01

    The Source/Loss Cone Energetic Particle Spectrometer (SEPS) on the Polar Satellite observes ions above 155 keV with an angular resolution of about 1.5 degrees. When the axis of SEPS is pointing within 10 degrees of the magnetic field direction, the detector measures particles in both the downward and upward loss cones. Measurements of the loss cone fluxes during the magnetic storms of August 6, 1998, August 27, 1998, September 25, 1998, October 19, 1998, and November 13, 1998 often show large fluxes of ring current ions moving downward inside the loss cone. At times these fluxes are comparable to the trapped ion population, indicating that strong pitch angle scattering is taking place at least locally. Although Polar encounters the ring current region at only two magnetic local times during any given storm, the frequent observation of precipitation suggests that pitch angle scattering is an important loss mechanism for ring current ions.

  17. Pitch-angle scattering of energetic particles with adiabatic focusing

    SciTech Connect

    Tautz, R. C.; Shalchi, A.; Dosch, A. E-mail: andreasm4@yahoo.com

    2014-10-20

    Understanding turbulent transport of charged particles in magnetized plasmas often requires a model for the description of random variations in the particle's pitch angle. The Fokker-Planck coefficient of pitch-angle scattering, which is used to describe scattering parallel to the mean magnetic field, is therefore of central importance. Whereas quasi-linear theory assumes a homogeneous mean magnetic field, such a condition is often not fulfilled, especially for high-energy particles. Here, a new derivation of the quasi-linear approach is given that is based on the unperturbed orbit found for an adiabatically focused mean magnetic field. The results show that, depending on the ratio of the focusing length and the particle's Larmor radius, the Fokker-Planck coefficient is significantly modified but agrees with the classical expression in the limit of a homogeneous mean magnetic field.

  18. 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.

  19. Determining Equilibrium Lamellar Thickness by Small Angle Light Scattering

    NASA Astrophysics Data System (ADS)

    Li, Ying; Akpalu, Yvonne

    2002-03-01

    The crystallization and melting behavior of homogeneous copolymers of ethylene with butene and hexene is studied by small angle light scattering (SALS). We show that the final melting temperature (T_m^f), which corresponds to equilibrium between a melt with an overall ethylene sequence concentration (equal to the mole fraction of crystallizable units) and the thickest lamellar crystals can be determined from the SALS melting measurements. The T_m^f values, determined from the temperature at which the SALS HV or VV invariant vanishes during the melting, are substantially higher (7 to 10 °C) than those obtained from small angle x-ray (SAXS), wide angle x-ray scattering (WAXS) and differential scanning calorimetry (DSC). Thus our measurements indicate that SAXS, WAXS and DSC underestimate the lamellar thickness (l_f) of the largest crystals, a parameter necessary for estimating thermodynamic and kinetic parameters for ethylene copolymers. We also investigate T_m^f as a function of crystallization time (ranging from 1 hr to 72 hr) and heating rate. We discuss the implications of our SALS approach for estimating T_m^f, lf and lamellar morphological parameters from x-ray scattering.

  20. 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.

  1. Small-angle scattering studies of meso-scopic structures with synchrotron X-rays

    NASA Astrophysics Data System (ADS)

    Dore, J. C.; North, A. N.; Rigden, J. S.

    1995-03-01

    The use of small-angle X-ray scattering techniques for the study of spatial inhomogeneities over the range 20 Å to 2 μm is reviewed. The basic formalism for scattering by an inhomogeneous medium is developed with particular reference to liquid suspensions, porous solids and solid aggregates. The instrumentation available on the Synchrotron Radiation Source at the Daresbury Laboratory is briefly presented and the use of the Bonse-Hart method for studies at ultra-low scattering angles described. The extraction of structural information for a range of natural and synthetic materials is presented with particular reference to microemulsions, porous silicas, clays and composites. The complementarity of X-ray and neutron techniques is critically reviewed and prospects for future developments, particularly for the study of anisotropic systems, are discussed.

  2. Limiting cases of the small-angle scattering approximation solutions for the propagation of laser beams in anisotropic scattering media

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Deepak, A.

    1981-01-01

    The propagation of photons in a medium with strongly anisotropic scattering is a problem with a considerable history. Like the propagation of electrons in metal foils, it may be solved in the small-angle scattering approximation by the use of Fourier-transform techniques. In certain limiting cases, one may even obtain analytic expressions. This paper presents some of these results in a model-independent form and also illustrates them by the use of four different phase-function models. Sample calculations are provided for comparison purposes

  3. Pitch-angle scattering in magnetostatic turbulence. II. Analytical considerations and pitch-angle isotropization

    NASA Astrophysics Data System (ADS)

    Tautz, R. C.

    2013-10-01

    Aims: The process of pitch-angle isotropization is important for many applications ranging from diffusive shock acceleration to large-scale cosmic-ray transport. Here, the basic analytical description is revisited on the basis of recent simulation results. Methods: Both an analytical and a numerical investigation were undertaken of the Fokker-Planck equation for pitch-angle scattering. Additional test-particle simulations obtained with the help of a Monte-Carlo code were used to verify the conclusions. Results: It is shown that the usual definition of the pitch-angle Fokker-Planck coefficient via the mean-square displacement is flawed. The reason can be traced back to the assumption of homogeneity in time which does not hold for pitch-angle scattering. Conclusions: Calculating the mean free path via the Fokker-Planck coefficient has often proven to give an accurate description. For numerical purposes, accordingly, it is the definition that has to be exchanged in favor of the pitch-angle correlation function.

  4. Measuring the distribution of cellulose microfibril angles in primary cell walls by small angle X-ray scattering

    PubMed Central

    2014-01-01

    Background X-ray scattering is a well-established method for measuring cellulose microfibril angles in secondary cell walls. However, little data is available on the much thinner primary cell walls. Here, we show that microfibril orientation distributions can be determined by small angle X-ray scattering (SAXS) even in primary cell walls. The technique offers a number of advantages: samples can be analyzed in the native hydrated state without any preparation which minimizes the risk of artifacts and allows for fast data acquisition. The method provides data averaged over a specimen region, determined by the size of the used X-ray beam and, thus, yields the microfibril orientation distribution within this region. Results Cellulose microfibril orientation distributions were obtained for single cells of the alga Chara corallina, as well as for the multicellular hypocotyl of Arabidopsis thaliana. In both, Chara and Arabidopsis, distributions with a broad scattering around mean microfibril angles of approximately 0° and 90° towards the longitudinal axis of the cells were found. Conclusions With SAXS, the structure of primary cell walls can be analysed in their native state and new insights into the cellulose microfibril orientation of primary cell walls can be gained. The data shows that SAXS can serve as a valuable tool for the analysis of cellulose microfibril orientation in primary cell walls and, in consequence, add to the understanding of its mechanical behaviour and the intriguing mechanisms behind cell growth. PMID:25170343

  5. 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.

  6. 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.

  7. 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

  8. Modeling Electron Pitch-Angle Scattering Rates by EMIC Waves

    NASA Astrophysics Data System (ADS)

    Usanova, Maria; Shprits, Yuri; Drozdov, Alexander

    2016-07-01

    The response of electron fluxes to different geomagnetic activity is determined by competing electron acceleration and loss processes. Interaction with EMIC waves is believed to be an important loss mechanism for the radiation belt electrons, which can undergo cyclotron resonance with EMIC waves and consequent pitch-angle scattering into the atmosphere. The recent study by Usanova et al. [2014] reported the first definitive proof of EMIC waves scattering electrons into the atmosphere. These new results are particularly interesting and significant as EMIC is the only wave mode that can scatter ultra-relativistic electrons much faster and more efficient than other wave modes (e.g., chorus and hiss) and therefore, is supposed to be a dominant internal loss mechanism for ˜>2 MeV energy electrons. In this talk we will focus on numerical modeling of EMIC-related electron losses. We compute bounce-averaged pitch-angle diffusion coefficients of electrons due to EMIC waves using a quasi-linear approach and use these coefficients as further input to the Versatile Electron Radiation Belt (VERB) diffusion code to simulate the evolution of electron phase space density during selected events. We will present a comparison of the simulation results and observed pitch angle distributions on the Van Allen Probes during selected events. We will also address the following questions: Where and under which conditions signatures of EMIC-related electron loss are typically observed? What are the EMIC wave and background plasma parameters required for this interaction? Can we reproduce observed losses of radiation belt electrons using numerical modeling?

  9. Structural investigations of fat fractals using small-angle scattering

    NASA Astrophysics Data System (ADS)

    Anitas, Eugen M.

    2015-01-01

    Experimental small-angle scattering (SAS) data characterized, on a double logarithmic scale, by a succession of power-law decays with decreasing values of scattering exponents, can be described in terms of fractal structures with positive Lebesgue measure (fat fractals). Here we present a theoretical model for fat fractals and show how one can extract structural information about the underlying fractal using SAS method, for the well known fractals existing in the literature: Vicsek and Menger sponge. We calculate analytically the fractal structure factor and study its properties in momentum space. The models allow us to obtain the fractal dimension at each structural level inside the fractal, the number of particles inside the fractal and about the most common distances between the center of mass of the particles.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Dual-angle, self-calibrating Thomson scattering measurements in RFX-MOD

    SciTech Connect

    Giudicotti, L.

    2014-11-15

    In the multipoint Thomson scattering (TS) system of the RFX-MOD experiment the signals from a few spatial positions can be observed simultaneously under two different scattering angles. In addition the detection system uses optical multiplexing by signal delays in fiber optic cables of different length so that the two sets of TS signals can be observed by the same polychromator. Owing to the dependence of the TS spectrum on the scattering angle, it was then possible to implement self-calibrating TS measurements in which the electron temperature T{sub e}, the electron density n{sub e} and the relative calibration coefficients of spectral channels sensitivity C{sub i} were simultaneously determined by a suitable analysis of the two sets of TS data collected at the two angles. The analysis has shown that, in spite of the small difference in the spectra obtained at the two angles, reliable values of the relative calibration coefficients can be determined by the analysis of good S/N dual‑angle spectra recorded in a few tens of plasma shots. This analysis suggests that in RFX-MOD the calibration of the entire set of TS polychromators by means of the similar, dual-laser (Nd:YAG/Nd:YLF) TS technique, should be feasible.

  15. Dual-angle, self-calibrating Thomson scattering measurements in RFX-MOD

    NASA Astrophysics Data System (ADS)

    Giudicotti, L.; Pasqualotto, R.; Fassina, A.

    2014-11-01

    In the multipoint Thomson scattering (TS) system of the RFX-MOD experiment the signals from a few spatial positions can be observed simultaneously under two different scattering angles. In addition the detection system uses optical multiplexing by signal delays in fiber optic cables of different length so that the two sets of TS signals can be observed by the same polychromator. Owing to the dependence of the TS spectrum on the scattering angle, it was then possible to implement self-calibrating TS measurements in which the electron temperature Te, the electron density ne and the relative calibration coefficients of spectral channels sensitivity Ci were simultaneously determined by a suitable analysis of the two sets of TS data collected at the two angles. The analysis has shown that, in spite of the small difference in the spectra obtained at the two angles, reliable values of the relative calibration coefficients can be determined by the analysis of good S/N dual-angle spectra recorded in a few tens of plasma shots. This analysis suggests that in RFX-MOD the calibration of the entire set of TS polychromators by means of the similar, dual-laser (Nd:YAG/Nd:YLF) TS technique, should be feasible.

  16. 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.

  17. Small angle x-ray scattering with edge-illumination

    PubMed Central

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-01-01

    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. PMID:27491917

  18. 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.

  19. Small angle x-ray scattering with edge-illumination.

    PubMed

    Modregger, Peter; Cremona, Tiziana P; Benarafa, Charaf; Schittny, Johannes C; Olivo, Alessandro; Endrizzi, Marco

    2016-01-01

    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. PMID:27491917

  20. High-resolution angle-resolved measurements of light scattered at small angles by red blood cells in suspension.

    PubMed

    Turcu, Ioan; Pop, Cristian V L; Neamtu, Silvia

    2006-03-20

    Red blood cells (RBCs) scatter light mainly in the forward direction, where the scattering phase function has a narrow peak. We performed an experimental investigation into the angular distribution of light scattered by blood in the small-angle domain. A highly diluted suspension of RBCs (hematocrits in the range 5 x 10(-5)-10(-2)) was illuminated with a He-Ne laser with 633 nm wavelength. We focused our research on two main topics: the scattering efficiency of the RBCs given by the mean scattering cross section and the scattering anisotropy obtained from the angular distribution of the scattered photons. The collimated beam transmission and the angular distribution of scattered light were measured and compared with the predictions of the effective phase function model. The RBCs' mean scattering cross section and scattering anisotropy were obtained by fitting of the experimental data. PMID:16579566

  1. A polarization-based Thomson scattering technique for burning plasmas

    NASA Astrophysics Data System (ADS)

    Parke, E.; Mirnov, V. V.; Den Hartog, D. J.

    2014-02-01

    The traditional Thomson scattering diagnostic is based on measurement of the wavelength spectrum of scattered light, where electron temperature measurements are inferred from thermal broadening of the spectrum. At sufficiently high temperatures, especially those predicted for ITER and other burning plasmas, relativistic effects cause a change in the degree of polarization (P) of the scattered light; for fully polarized incident laser light, the scattered light becomes partially polarized. The resulting reduction of polarization is temperature dependent and has been proposed by other authors as a potential alternative to the traditional spectral decomposition technique. Following the previously developed Stokes vector approach, we analytically calculate the degree of polarization for incoherent Thomson scattering. For the first time, we obtain exact results valid for the full range of incident laser polarization states, scattering angles, and electron temperatures. While previous work focused only on linear polarization, we show that circularly polarized incident light optimizes the degree of depolarization for a wide range of temperatures relevant to burning plasmas. We discuss the feasibility of a polarization based Thomson scattering diagnostic for ITER-like plasmas with both linearly and circularly polarized light and compare to the traditional technique.

  2. 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.

  3. A novel small-angle neutron scattering detector geometry.

    PubMed

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

    2013-08-01

    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 (3)He, the new concept utilizes gaseous detectors with (10)B 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.

  4. 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

  5. Wide Angle Compton Scattering within the SCET factorization Framework

    NASA Astrophysics Data System (ADS)

    Kivel, Nikolay

    2016-03-01

    Existing data for the electromagnetic proton form factors and for the cross section of the wide angle Compton scattering (WACS) show that the hard two-gluon exchange mechanism (collinear factorization) is still not applicable in the kinematical region where Mandelstam variables s ~ -t ~ -u are about few GeV2. On the other hand these observables can be described in phenomenological models where spectator quarks are soft which assumes a large contribution due to the soft-overlap mechanism. It turns out that the simple QCD factorization picture is not complete and must also include the soft-overlap contribution which can be described as a certain matrix element in the soft collinear effective theory (SCET). Then the leading power contribution to WACS amplitude is described as a sum of the hard- and soft-spectator contributions. The existing experimental data allows one to check certain conclusions based on the assumption about dominant role of the soft-spectator mechanism.

  6. Magnetic small-angle neutron scattering of bulk ferromagnets.

    PubMed

    Michels, Andreas

    2014-09-24

    We summarize recent theoretical and experimental work in the field of magnetic small-angle neutron scattering (SANS) of bulk ferromagnets. The response of the magnetization to spatially inhomogeneous magnetic anisotropy and magnetostatic stray fields is computed using linearized micromagnetic theory, and the ensuing spin-misalignment SANS is deduced. Analysis of experimental magnetic-field-dependent SANS data of various nanocrystalline ferromagnets corroborates the usefulness of the approach, which provides important quantitative information on the magnetic-interaction parameters such as the exchange-stiffness constant, the mean magnetic anisotropy field, and the mean magnetostatic field due to jumps ΔM of the magnetization at internal interfaces. Besides the value of the applied magnetic field, it turns out to be the ratio of the magnetic anisotropy field Hp to ΔM, which determines the properties of the magnetic SANS cross-section of bulk ferromagnets; specifically, the angular anisotropy on a two-dimensional detector, the asymptotic power-law exponent, and the characteristic decay length of spin-misalignment fluctuations. For the two most often employed scattering geometries where the externally applied magnetic field H0 is either perpendicular or parallel to the wave vector k0 of the incoming neutron beam, we provide a compilation of the various unpolarized, half-polarized (SANSPOL), and uniaxial fully-polarized (POLARIS) SANS cross-sections of magnetic materials. PMID:25180625

  7. 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

    2015-01-01

    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. PMID:26160052

  8. Small-angle neutron scattering at pulsed spallation sources

    SciTech Connect

    Seeger, P.A.; Hjelm, R.P. Jr.

    1990-01-01

    The importance of small-angle neutron scattering (SANS) in biological, chemical, physical, and engineering research mandates that all intense neutron sources be equipped with SANS instruments. Four existing instruments are described, and the general differences between pulsed-source and reactor-based instrument designs are discussed. The basic geometries are identical, but dynamic range is achieved by using a broad band of wavelengths (with time-of-flight analysis) rather than by moving the detector. This allows a more optimized collimation system. Data acquisition requirements at a pulsed source are more severe, requiring large, fast histogramming memories. Data reduction is also more complex, as all wave length-dependent and angle-dependent backgrounds and non-linearities must be accounted for before data can be transformed to intensity vs Q. A comparison is shown between the Los Alamos pulsed instrument and D-11 (Institute Laue-Langevin), and examples from the four major topics of the conference are shown. The general conclusion is that reactor-based instruments remain superior at very low Q or if only a narrow range of Q is required, but that the current generation of pulsed-source instruments is competitive at moderate Q and may be faster when a wide range of Q is required. In principle, a user should choose which facility to use on the basis of optimizing the experiment; in practice the tradeoffs are not severe and the choice is usually made on the basis of availability.

  9. Dual wavelength multiple-angle light scattering system for cryptosporidium detection

    NASA Astrophysics Data System (ADS)

    Buaprathoom, S.; Pedley, S.; Sweeney, S. J.

    2012-06-01

    A simple, dual wavelength, multiple-angle, light scattering system has been developed for detecting cryptosporidium suspended in water. Cryptosporidium is a coccidial protozoan parasite causing cryptosporidiosis; a diarrheal disease of varying severity. The parasite is transmitted by ingestion of contaminated water, particularly drinking-water, but also accidental ingestion of bathing-water, including swimming pools. It is therefore important to be able to detect these parasites quickly, so that remedial action can be taken to reduce the risk of infection. The proposed system combines multiple-angle scattering detection of a single and two wavelengths, to collect relative wavelength angle-resolved scattering phase functions from tested suspension, and multivariate data analysis techniques to obtain characterizing information of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs two diode lasers (violet InGaN-based and red AlGaInP-based) as light sources and silicon photodiodes as detectors and optical components, all of which are readily available. The measured scattering patterns using the dual wavelength system showed that the relative wavelength angle-resolved scattering pattern of cryptosporidium oocysts was significantly different from other particles (e.g. polystyrene latex sphere, E.coli). The single wavelength set up was applied for cryptosporidium oocysts'size and relative refractive index measurement and differential measurement of the concentration of cryptosporidium oocysts suspended in water and mixed polystyrene latex sphere suspension. The measurement results showed good agreement with the control reference values. These results indicate that the proposed method could potentially be applied to online detection in a water quality control system.

  10. Small-angle scattering for structural biology—Expanding the frontier while avoiding the pitfalls

    PubMed Central

    Jacques, David A; Trewhella, Jill

    2010-01-01

    The last decade has seen a dramatic increase in the use of small-angle scattering for the study of biological macromolecules in solution. The drive for more complete structural characterization of proteins and their interactions, coupled with the increasing availability of instrumentation and easy-to-use software for data analysis and interpretation, is expanding the utility of the technique beyond the domain of the biophysicist and into the realm of the protein scientist. However, the absence of publication standards and the ease with which 3D models can be calculated against the inherently 1D scattering data means that an understanding of sample quality, data quality, and modeling assumptions is essential to have confidence in the results. This review is intended to provide a road map through the small-angle scattering experiment, while also providing a set of guidelines for the critical evaluation of scattering data. Examples of current best practice are given that also demonstrate the power of the technique to advance our understanding of protein structure and function. PMID:20120026

  11. 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.

  12. Small angle scattering methods to study porous materials under high uniaxial strain.

    PubMed

    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.

  13. Low-angle X-ray scattering properties of irradiated spices

    NASA Astrophysics Data System (ADS)

    Almeida, A. P. G.; Braz, D.; Barroso, R. C.; Lopes, R. T.

    2007-09-01

    The scattering of X-rays at low angles (LAXS) is a technique dominated by the coherent scattering process. One characteristic observation of low-angle coherent scattering is the so-called molecular interference effect, being characterized by the presence of one or more peaks in the forward direction of scattering. In the present study, LAXS profiles from five different spices are carefully measured in order to establish characteristic scattering signatures. Samples of Ceylon cinnamon, cumin, nutmeg, paprika and black pepper were bought in local market in Rio de Janeiro, Brazil. The LAXS patterns were obtained using a Shimadzu DRX 6000 diffractometer in reflection geometry. Coherent scattering patterns are measured for the samples for θ=5-35°. The data were collected in 0.05° increments every 3 s. In order to evaluate the possible molecular structure changes caused to the irradiation procedure, the signatures obtained for control (non-irradiated) spices were compared with spice samples irradiated with different doses varying from 3 to 40 kGy. The LAXS patterns of all samples were obtained after 30, 60, 90, 120 days to evaluate the effect of storage period. Scattering profiles from spices irradiated with different irradiation doses were obtained and the results compared. For each spice, there is no considerable deviation in shape in function of the irradiation dose. It indicates that the molecular structure of each analyzed spices is preserved considering the dose range chosen. The results show that the molecular structure was found to be stable during storage at the ambient temperature for up to 4 months.

  14. Effect of shadowing on electromagnetic scattering from rough ocean wavelike surfaces at small grazing angles

    SciTech Connect

    West, J.C.

    1997-03-01

    A hybrid moment-method/geometrical-theory-of-diffraction technique (MM/GTD) has been implemented to numerically calculate the electromagnetic scattering from one-dimensionally rough surfaces at extreme illumination angles (down to 0{degree} grazing). The hybrid approach allows the extension of the modeled scattering surface to infinity, avoiding the artificial edge diffraction that prevents use of the standard moment method at the smallest grazing angles. Numerical calculation of the backscattering from slightly rough large-scale surfaces approximating ocean wave features shows that roughness in strongly shadowed regions can contribute significantly to the total backscatter at vertical polarization. This is observed when the shadowing obstacle is several wavelengths high, and the magnitude of the shadow-region contribution does not depend on the radius-of-curvature of the shadowing feature. Strongly shadowed roughness does not significantly contribute to the backscatter at horizontal polarization, although weakly shadowed roughness near the incidence shadow boundary does. The calculations indicate that a shadowing-corrected two-scale model may be able to predict the distributed-surface portion of the sea-surface scattering from the ocean surface at grazing angles down to about 15{degree}, but at lower grazing the shadowing and large-scale curvature of the surface prevent the establishment of a Bragg resonance and invalidate the model.

  15. Inelastic scattering of NO from Ag(111): Internal state, angle, and velocity resolved measurements

    SciTech Connect

    Rettner, C.T.; Kimman, J.; Auerbach, D.J. )

    1991-01-01

    We have determined the velocity distributions of individual quantum states of NO scattering from Ag(111) at specific scattering angles {theta}{sub {ital f}} using molecular beam techniques to control the incidence energy {ital E}{sub {ital i}} and angle {theta}{sub {ital i}}. We find that the mean energies of scattered species {ital E}{sub {ital f}} depend weakly on {theta}{sub {ital f}} at low collision energies, but become increasingly independent of this parameter as {ital E}{sub {ital i}} approaches 1.0 eV. This is true for all final rotation states {ital J}. The previously reported insensitivity of the final kinetic energy to {ital J} is found to apply at all scattering angles, so that {ital E}{sub {ital f}} vs {theta}{sub {ital f}} curves for high {ital J} fall only slightly below those for low {ital J}. This system is highly translationally inelastic at high incidence energies, with up to 55% of {ital E}{sub {ital i}} being lost to phonons at {ital E}{sub {ital i}}=1.0 eV. Angular distributions are relatively insensitive to {ital J} at low {ital E}{sub {ital i}} , but for high {ital E}{sub {ital i}} the peak flux is found to shift away from the surface normal as {ital E}{sub {ital i}} increases. The effect of the surface temperature only becomes apparent at low incidence energies. A search for supernumerary rotational rainbows reveals no discernible oscillations even for the lowest surface temperatures. We believe that these supernumerary oscillations may be damped by surface corrugation'' effects for this system. Discussion focuses on the observed anticorrelation between kinetic energy transfer to phonons and to rotation, the extent to which parallel momentum is conserved in this system, and energy-angle scaling laws for energy transfer.

  16. Sizing aerosolized fractal nanoparticle aggregates through Bayesian analysis of wide-angle light scattering (WALS) data

    NASA Astrophysics Data System (ADS)

    Huber, Franz J. T.; Will, Stefan; Daun, Kyle J.

    2016-11-01

    Inferring the size distribution of aerosolized fractal aggregates from the angular distribution of elastically scattered light is a mathematically ill-posed problem. This paper presents a procedure for analyzing Wide-Angle Light Scattering (WALS) data using Bayesian inference. The outcome is probability densities for the recovered size distribution and aggregate morphology parameters. This technique is applied to both synthetic data and experimental data collected on soot-laden aerosols, using a measurement equation derived from Rayleigh-Debye-Gans fractal aggregate (RDG-FA) theory. In the case of experimental data, the recovered aggregate size distribution parameters are generally consistent with TEM-derived values, but the accuracy is impaired by the well-known limited accuracy of RDG-FA theory. Finally, we show how this bias could potentially be avoided using the approximation error technique.

  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. 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.

  19. Small Angle Neutron Scattering of Solutions of Arborescent Graft Polymers

    NASA Astrophysics Data System (ADS)

    Choi, Sangwook; Briber, R. M.; Bauer, B. J.; Topp, Andreas; Gauthier, Mario

    1998-03-01

    Arborescent graft polymers are branched macromolecules resulting from successive cycles of chloromethylation and anionic grafting reactions. Small angle neutron scattering (SANS) was used to measure the size and shape of arborescent graft polymers in solution. Guinier plots were used to analyze the data at small q. The radius of gyration of arborescent graft polymers was found to be almost independent of temperature as the solution was cooled towards the phase separation temperature. The optical cloud point temperature was found to be 15 ^0C. At the phase separation temperature two peaks were observed in the I versus q SANS data. The first peak is due to the interference between molecules while the second peak comes from the single particle form factor. The value of q at the peak from the form factor was almost constant as temperature was changed from 40 ^0C to 20 ^0C. The peak position shifted to higher q at the phase separation temperature. This indicates that the size of molecules decreased as the molecules began to aggregate below the phase separation temperature. The value of A2 for arborescent graft polymers was found to be independent of temperature and close to zero.

  20. Numerical Techniques for Scattering from Submerged Objects

    NASA Technical Reports Server (NTRS)

    Werby, M. F.; Tango, G. J.; Gaunaurd, G. C.

    1985-01-01

    To represent the final results in terms of matrices, one expands all appropriate physical quantities in terms of partial wave basis states. This includes expansions for the incident and scattered fields and the surface quantities. The method then utilizes the Huygen-Poincare integral representation for both the exterior and interior solutions, leading to the required matrix equations. One thus deals with matrix equations, the complexity of which depends on the nature of the problem. It is shown that in general a transition matrix T can be obtained relating the incident field A with the scattered field f having the form T = PQ(-1), where f = TA. The structure of Q can be quite complicated and can itself be composed of other matrix inversions such as arise from layered objects. Recent improvements in this method appropriate for a variety of physical problems are focused on, and on their implementation. Results are outlined from scattering simulations for very elongated submerged objects and resonance scattering from elastic solids and shells. The final improvement concerns eigenfunction expansions of surface terms, arising from solution of the interior problem, obtained via a preconditioning technique. This effectively reduces the problem to that of obtaining eigenvalues of a Hermitian operator. This formalism is reviewed for scattering from targets that are rigid, sound-soft, acoustic, elastic solids, elastic shells, and elastic layered objects. Two sets of the more interesting results are presented. The first concerns scattering from elongated objects, and the second to thin elastic spheroids.

  1. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators

    PubMed Central

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2015-01-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300−2500 nm at incidence angles 15–60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0–60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350–1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article “Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators” in Solar Energy Materials and Solar Cells. PMID:26862556

  2. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

    PubMed

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2016-03-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Anovitz, Lawrence M.; Lynn, Gary W.; Cole, David R.; Rother, Gernot; Allard, Lawrence F.; Hamilton, William A.; Porcar, Lionel; Kim, Man-Ho

    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 ˜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 in a

  7. 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.

  8. Angle-resolved scattering spectroscopy of explosives using an external cavity quantum cascade laser

    SciTech Connect

    Suter, Jonathan D.; Bernacki, Bruce E.; Phillips, Mark C.

    2012-04-01

    Investigation of angle-resolved scattering from solid explosives residues on a car door for non-contact sensing geometries. Illumination with a mid-infrared external cavity quantum cascade laser tuning between 7 and 8 microns was detected both with a sensitive single point detector and a hyperspectral imaging camera. Spectral scattering phenomena were discussed and possibilities for hyperspectral imaging at large scattering angles were outlined.

  9. 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.

  10. Forward-angle neutron-proton scattering at 96 MeV

    SciTech Connect

    Johansson, C.; Blomgren, J.; Atac, A.; Bergenwall, B.; Hildebrand, A.; Klug, J.; Mermod, P.; Pomp, S.; Oesterlund, M.; Dangtip, S.; Tippawan, U.; Elmgren, K.; Jonsson, O.; Prokofiev, A.V.; Renberg, P.-U.; Nadel-Turonski, P.; Nilsson, L.; Olsson, N.

    2005-02-01

    The differential np scattering cross section has been measured at 96 MeV in the angular range {theta}{sub c.m.}=20 deg. -76 deg. Together with an earlier data set at the same energy, covering the angles {theta}{sub c.m.}=74 deg. -180 deg., a new data set has been formed in the angular range {theta}{sub c.m.}=20 deg. - 180 deg. This extended data set has been normalized to the experimental total np cross section, resulting in a renormalization of the earlier data of 0.7%, which is well within the reported normalization uncertainty for that experiment. A novel normalization technique has been investigated. The results on forward np scattering are in reasonable agreement with theory models and partial wave analyses and have been compared with data from the literature.

  11. Elevation angle alignment of quasi optical receiver mirrors of collective Thomson scattering diagnostic by sawtooth measurementsa)

    NASA Astrophysics Data System (ADS)

    Moseev, D.; Meo, F.; Korsholm, S. B.; Bindslev, H.; Furtula, V.; Kantor, M.; Leipold, F.; Michelsen, P. K.; Nielsen, S. K.; Salewski, M.; Stejner, M.

    2012-10-01

    Localized measurements of the fast ion velocity distribution function and the plasma composition measurements are of significant interest for the fusion community. Collective Thomson scattering (CTS) diagnostics allow such measurements with spatial and temporal resolution. Localized measurements require a good alignment of the optical path in the transmission line. Monitoring the alignment during the experiment greatly benefits the confidence in the CTS measurements. An in situ technique for the assessment of the elevation angle alignment of the receiver is developed. Using the CTS diagnostic on TEXTOR without a source of probing radiation in discharges with sawtooth oscillations, an elevation angle misalignment of 0.9° was found with an accuracy of 0.25°.

  12. Aerosol particle analysis by Raman scattering technique

    SciTech Connect

    Fung, K.H.; Tang, I.N.

    1992-10-01

    Laser Raman spectroscopy is a very versatile tool for chemical characterization of micron-sized particles. Such particles are abundant in nature, and in numerous energy-related processes. In order to elucidate the formation mechanisms and understand the subsequent chemical transformation under a variety of reaction conditions, it is imperative to develop analytical measurement techniques for in situ monitoring of these suspended particles. In this report, we outline our recent work on spontaneous Raman, resonance Raman and non-linear Raman scattering as a novel technique for chemical analysis of aerosol particles as well as supersaturated solution droplets.

  13. A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses

    NASA Astrophysics Data System (ADS)

    Walker, Bennett N.; James, Robert H.; Calogero, Don; Ilev, Ilko K.

    2015-09-01

    Glare, glistenings, optical defects, dysphotopsia, and poor image quality are a few of the known deficiencies of intraocular lenses (IOLs). All of these optical phenomena are related to light scatter. However, the specific direction that light scatters makes a critical difference between debilitating glare and a slightly noticeable decrease in image quality. Consequently, quantifying the magnitude and direction of scattered light is essential to appropriately evaluate the safety and efficacy of IOLs. In this study, we introduce a full-angle scanning light scattering profiler (SLSP) as a novel approach capable of quantitatively evaluating the light scattering from IOLs with a nearly 360° view. The SLSP method can simulate in situ conditions by controlling the parameters of the light source including angle of incidence. This testing strategy will provide a more effective nonclinical approach for the evaluation of IOL light scatter.

  14. A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses

    SciTech Connect

    Walker, Bennett N.; James, Robert H.; Ilev, Ilko K.; Calogero, Don

    2015-09-15

    Glare, glistenings, optical defects, dysphotopsia, and poor image quality are a few of the known deficiencies of intraocular lenses (IOLs). All of these optical phenomena are related to light scatter. However, the specific direction that light scatters makes a critical difference between debilitating glare and a slightly noticeable decrease in image quality. Consequently, quantifying the magnitude and direction of scattered light is essential to appropriately evaluate the safety and efficacy of IOLs. In this study, we introduce a full-angle scanning light scattering profiler (SLSP) as a novel approach capable of quantitatively evaluating the light scattering from IOLs with a nearly 360° view. The SLSP method can simulate in situ conditions by controlling the parameters of the light source including angle of incidence. This testing strategy will provide a more effective nonclinical approach for the evaluation of IOL light scatter.

  15. Small Angle X-ray Scattering in Structural Investigation of Selected Biological Systems

    SciTech Connect

    Kozak, Maciej

    2007-11-26

    Small angle X-ray scattering method (SAXS) is a technique complementary to the protein crystallography, allowing determination of the structural parameters such as the radius of gyration or the maximum size characterizing the macromolecules, and providing information on the conformational changes taking place in solution. The use of SAXS method enables a comparison of the protein crystal structure with the data collected in solution. Recent development of the measurement techniques (mainly those based on synchrotron radiation) and calculation methods has permitted introduction of advanced techniques also in the field of structural analysis of biomolecules (e.g. for determination of the shape of the protein molecule in solution). The paper presents a few selected methods of structural analysis of biological systems based on the SAXS data and illustrates their performance on the example of xylanase from Trichoderma longibrachiatum and a model phospholipid system.

  16. Small Angle X-ray Scattering in Structural Investigation of Selected Biological Systems

    NASA Astrophysics Data System (ADS)

    Kozak, Maciej

    2007-11-01

    Small angle X-ray scattering method (SAXS) is a technique complementary to the protein crystallography, allowing determination of the structural parameters such as the radius of gyration or the maximum size characterizing the macromolecules, and providing information on the conformational changes taking place in solution. The use of SAXS method enables a comparison of the protein crystal structure with the data collected in solution. Recent development of the measurement techniques (mainly those based on synchrotron radiation) and calculation methods has permitted introduction of advanced techniques also in the field of structural analysis of biomolecules (e.g. for determination of the shape of the protein molecule in solution). The paper presents a few selected methods of structural analysis of biological systems based on the SAXS data and illustrates their performance on the example of xylanase from Trichoderma longibrachiatum and a model phospholipid system.

  17. Versatile wide angle diffraction setup for simultaneous wide and small angle x-ray scattering measurements with synchrotron radiation

    SciTech Connect

    Rueda, D.R.; Garcia-Gutierrez, M.C.; Nogales, A.; Capitan, M.J.; Ezquerra, T.A.; Labrador, A.; Fraga, E.; Beltran, D.; Juanhuix, J.; Herranz, J.F.; Bordas, J.

    2006-03-15

    Here we present a novel, simple, and versatile experimental setup aimed to perform wide angle x-ray scattering (WAXS) measurements alone or in simultaneous combination with small angle x-ray scattering measurements. The design of the WAXS goniometer allows one to obtain high resolution diffraction patterns in a broad angular range. The setup can incorporate a hot stage in order to evaluate temperature resolved experiments. The performance of the equipment has been verified in the BM16 beam line of the European Synchrotron Radiation Facility with different well known samples such as alumina, isotropic film of high density polyethylene (HDPE), and oriented HPDE fiber.

  18. 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.

  19. 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.; 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 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

  20. Discovering New Features of Protein Complexes Structures by Small-Angle X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Oliveira, C. L. P.; Vorup-Jensen, T.; Andersen, C. B. F.; Andersen, G. R.; Pedersen, J. S.

    In spite of the recent advances in the X-Ray crystallography and nuclear magnetic resonance techniques, the determination of the quaternary structure of large protein complexes is still a challenge in molecular biology and biological sciences. In this respect, small-angle X-ray scattering (SAXS) is a key technique, enabling the determination of the possible structural conformation of complexes in an almost native state. Despite of this book being devoted to scattering techniques by synchrotron radiation, in this chapter we present two examples of application of laboratory-based SAXS to protein solution. The fundaments of the technique are obviously the same and have been deeply described in Chap. 2. In this chapter, we will introduce the application of SAXS to protein solution. Special emphasis is done on data reduction and absolute units calibration. As an example to illustrate the power of this technique, two new data sets for two protein complexes will be presented. This will show how high-quality SAXS data combined with advanced model strategies enables the determination of the quaternary structure of protein complexes.

  1. Small-Angle Neutron Scattering for Structural Biology of Protein-RNA Complexes.

    PubMed

    Gabel, Frank

    2015-01-01

    This chapter deals with the applications of small-angle neutron scattering (SANS) for the structural study of protein-RNA complexes in solution. After a brief historical introduction, the basic theory and practical requirements (e.g., sample state) for SANS experiments will be treated. Next, model-free parameters, such as the molecular mass and the radius of gyration, which can be obtained without a priori structural information, will be introduced. A more detailed section on the specific properties of SANS (with respect to its sister technique, small-angle X-ray scattering), and their implications on possibilities and limits of model building and interpretation will be discussed with a focus on protein-RNA systems. A practical illustration of the information content of SANS data will be given by applying ab initio modeling to a tRNA-synthetase system of known high-resolution structure. Finally, two present state-of-the-art examples that combine SANS data with complementary structural biology techniques (NMR and crystallography) will be presented and possible future developments and applications will be discussed.

  2. Irradiation Induced Defect Characterization in Reactor Pressure Vessel Steel by Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Han, Yougn-Soo; Shin, Eun-Joo; Lee, Chang-Hee; Park, Duck-Gun

    The degradation of the mechanical properties of the RPV (Reactor Pressure Vessel) steel during an irradiation in a nuclear power plant is closely related to the irradiation induced defects. The size of these defects is known to be a few nanometer, and the small angle neutron scattering technique is regarded as the best non destructive technique to characterize the nano sized inhomogeneities in bulk samples. The investigated the RPV steel has been used in YeongKwang nuclear power plant at Korea and the Cu content of the RPV steel is 0.06 wt%. The RPV steel was irradiated in the HANARO reactor at KAERI. The small angle neutron scattering experiments were performed by the SANS instrument in the HANARO reactor. The nano sized irradiation induced defects were quantitatively analyzed by SANS and the type of the irradiation induced defects was discussed in detail. The relation between irradiation induced defects and the yield strength was investigated. The characteristics of irradiation induced defects in low Cu containing RPV steel were discussed.

  3. Small-angle scattering studies of the pore spaces of shaly rocks

    NASA Astrophysics Data System (ADS)

    Hall, Peter L.; Mildner, David F. R.; Borst, Roger L.

    1986-02-01

    Small-angle neutron and X ray scattering (SANS and SAXS) measurements have been performed on shaly rocks from a variety of oil field locations. Thin core sections cut parallel to their bedding planes give circularly symmetric scattering patterns. On the basis of the model of Debye et al., the data indicate characteristic pore dimensions of 9-15 nm. Sections cut normal to the bedding planes exhibit elliptically symmetric scattering indicative of pores flattened in the direction of sedimentary compaction. Fourier inversion of the symmetric SANS data in all cases yields a broad distribution of pore diameters having peaks typically in the range 4-6 nm. These distributions are in reasonable agreement with distributions derived from nitrogen adsorption isotherms, although often in disagreement with nitrogen desorption or mercury porosimetry data. At higher scattering vectors, in the Porod region, differences between the SAXS and SANS data are observed which are explained in terms of the rather different sensitives of the two techniques to empty and filled pores. The data indicate that a significant component of the total porosity is due to pores of less than 2 nm in diameter, in which water is retained under ambient conditions. In several cases, pore dimensions measured by SANS increase after extraction of bitumens by methylene chloride solution, suggesting an intimate microscopic association of hydrocarbon and fine mineral grains.

  4. Fractal Structures on Fe3O4 Ferrofluid: A Small-Angle Neutron Scattering Study

    NASA Astrophysics Data System (ADS)

    Giri Rachman Putra, Edy; Seong, Baek Seok; Shin, Eunjoo; Ikram, Abarrul; Ani, Sistin Ari; Darminto

    2010-10-01

    A small-angle neutron scattering (SANS) which is a powerful technique to reveal the large scale structures was applied to investigate the fractal structures of water-based Fe3O4ferrofluid, magnetic fluid. The natural magnetite Fe3O4 from iron sand of several rivers in East Java Province of Indonesia was extracted and purified using magnetic separator. Four different ferrofluid concentrations, i.e. 0.5, 1.0, 2.0 and 3.0 Molar (M) were synthesized through a co-precipitation method and then dispersed in tetramethyl ammonium hydroxide (TMAH) as surfactant. The fractal aggregates in ferrofluid samples were observed from their SANS scattering distributions confirming the correlations to their concentrations. The mass fractal dimension changed from about 3 to 2 as ferrofluid concentration increased showing a deviation slope at intermediate scattering vector q range. The size of primary magnetic particle as a building block was determined by fitting the scattering profiles with a log-normal sphere model calculation. The mean average size of those magnetic particles is about 60 - 100 Å in diameter with a particle size distribution σ = 0.5.

  5. Challenges in the separation and analysis of scattered waves in angle-beam wavefield data

    SciTech Connect

    Dawson, Alexander J.; Michaels, Jennifer E.; Michaels, Thomas E.

    2015-03-31

    The measurement of ultrasonic signals on a 2-D rectilinear grid resulting from a fixed source, referred to as wavefield imaging, is a powerful tool for visualizing wave propagation and scattering. Wavefield imaging provides a more complete picture of wave propagation than conventional single-point measurements, but creates more challenges for analysis. This work considers the development of wavefield-based methods for analyzing angle-beam wave propagation and scattering in plates. Methods of analysis focus on the separation of scattered waves from the total wavefield with the eventual goal of quantitative scatterer characterization in a laboratory environment. Two methods for wave separation are considered: frequency-wavenumber filtering and wavefield baseline subtraction. Frequency-wavenumber filtering is applied to wavefield data that are finely sampled in both space and time, whereas baseline subtraction is a technique that has typically been applied to individual signals recorded from fixed transducers rather than to full wavefield data. Baseline subtraction of wavefields, particularly for the frequency range considered here, is sensitive to both specimen alignment and temperature variations, whereas frequency-wavenumber methods are limited in their ability to separate waves traveling in the same direction. Results are shown for both methods with a focus on investigating and overcoming the challenges to full wavefield baseline subtraction.

  6. Molecular differential cross sections for low angle photon scattering in tissues

    NASA Astrophysics Data System (ADS)

    Tartari, Agostino

    1999-08-01

    Measurements of molecular cross sections of coherently scattered photons were obtained by means of powder diffraction data analysis in the interval χ=0-6.4 nm -1 ( χ=sin( θ/2)/ λ; where θ is the scattering angle and λ the incident wavelength in units of nm). Accurate correction procedures were applied to the raw diffraction data. Data for fat and PMMA (polymethyl methacrylate)—reported in a previous analysis (Tartari A, Casnati E, Bonifazzi C, Baraldi C, 1997b. Phys. Med. Biol. 42, 2551-2560.—were found to agree quite well when compared to the results obtained with different quality of beams and analysis techniques. Investigation on bony tissue is presented for the first time, and a simple model has been carried out in order to segment the mineral and non-mineral components. Finally, a basic set of curves for the linear differential scattering coefficient is proposed in order to simulate photons scattering by tissue in terms of linear combination of such curves.

  7. Small-angle neutron scattering of nanocrystalline terbium with random paramagnetic susceptibility.

    PubMed

    Balaji, G; Ghosh, S; Döbrich, F; Eckerlebe, H; Weissmüller, J

    2008-06-01

    We report magnetic small-angle neutron scattering (SANS) data for the nanocrystalline rare earth metal Terbium in its paramagnetic state. Whereas critical scattering dominates at large momentum transfer, q, the (magnetic-) field response of the scattering at small q arises from the spatial nonuniformity of the paramagnetic susceptibility tensor. The finding of an interrelation between SANS and the susceptibility suggests a way for characterizing the nonuniform magnetic interactions in hard magnets by neutron scattering. PMID:18643454

  8. Energy dissipation and scattering angle distribution analysis of the classical trajectory calculations of methane scattering from a Ni(111) surface

    NASA Astrophysics Data System (ADS)

    Milot, Robin; Kleyn, A. W.; Jansen, A. P. J.

    2001-08-01

    We present classical trajectory calculations of the rotational vibrational scattering of a nonrigid methane molecule from a Ni(111) surface. Energy dissipation and scattering angles have been studied as a function of the translational kinetic energy, the incidence angle, the (rotational) nozzle temperature, and the surface temperature. Scattering angles are somewhat toward the surface for the incidence angles of 30°, 45°, and 60° at a translational energy of 96 kJ/mol. Energy loss is primarily from the normal component of the translational energy. It is transferred for somewhat more than half to the surface and the rest is transferred mostly to rotational motion. The spread in the change of translational energy has a basis in the spread of the transfer to rotational energy, and can be enhanced by raising of the surface temperature through the transfer process to the surface motion.

  9. SCT: a suite of programs for comparing atomistic models with small-angle scattering data

    PubMed Central

    Wright, David W.; Perkins, Stephen J.

    2015-01-01

    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. PMID:26089768

  10. 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

  11. Mapping the local nanostructure inside a specimen by tomographic small-angle x-ray scattering

    SciTech Connect

    Schroer, C.G.; Kuhlmann, M.; Roth, S.V.; Gehrke, R.; Stribeck, N.; Almendarez-Camarillo, A.; Lengeler, B.

    2006-04-17

    Small-angle x-ray scattering is combined with scanning microtomography to reconstruct the small-angle diffraction pattern in the direction of the tomographic rotation axis at each location on a virtual section through a specimen. These data yield information about the local nanoscale structure of the sample. With rotational symmetry present in the diffraction patterns, e.g., for isotropic or fiber-textured scatterers, the full reciprocal space information in the small-angle scattering regime can be reconstructed at each location inside the specimen. The method is illustrated investigating a polymer rod made by injection molding.

  12. 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.

  13. Spectral line polarization with angle-dependent partial frequency redistribution. III. Single scattering approximation for the Hanle effect

    NASA Astrophysics Data System (ADS)

    Sampoorna, M.

    2011-08-01

    Context. The solar limb observations in spectral lines display evidence of linear polarization, caused by non-magnetic resonance scattering process. This polarization is modified by weak magnetic fields - the process of the Hanle effect. These two processes serve as diagnostic tools for weak solar magnetic field determination. In modeling the polarimetric observations the partial frequency redistribution (PRD) effects in line scattering have to be accounted for. For simplicity, it is common practice to use PRD functions averaged over all scattering angles. For weak fields, it has been established that the use of angle-dependent PRD functions instead of angle-averaged functions is essential. Aims: We introduce a single scattering approximation to the problem of polarized line radiative transfer in weak magnetic fields with an angle-dependent PRD. This helps us to rapidly compute an approximate solution to the difficult and numerically expensive problem of polarized line formation with angle-dependent PRD. Methods: We start from the recently developed Stokes vector decomposition technique combined with the Fourier azimuthal expansion for angle-dependent PRD with the Hanle effect. In this decomposition technique, the polarized radiation field (I, Q, U) is decomposed into an infinite set of cylindrically symmetric Fourier coefficients tilde I(k)K_Q, where K = 0,2, with - K ≤ Q ≤ + K, and k is the order of the Fourier coefficients (k takes values from - ∞ to + ∞). In the single scattering approximation, the effect of the magnetic field on the Stokes I is neglected, so that it can be computed using the standard non-local thermodynamic equilibrium (non-LTE) scalar line transfer equation. In the case of angle-dependent PRD, we further assume that the Stokes I is cylindrically symmetric and given by its dominant term tilde I(0)0_0. Keeping only the contribution from tilde I(0)0_0 in the source terms for the K = 2 components (which give rise to Stokes Q and U), the

  14. Anomalous small-angle X-ray scattering of nanoporous two-phase atomistic models for amorphous silicon–germanium alloys

    SciTech Connect

    Chehaidar, A.

    2015-09-15

    The present work deals with a detailed analysis of the anomalous small-angle X-ray scattering in amorphous silicon–germanium alloy using the simulation technique. We envisage the nanoporous two-phase alloy model consisting in a mixture of Ge-rich and Ge-poor domains and voids at the nanoscale. By substituting Ge atoms for Si atoms in nanoporous amorphous silicon network, compositionally heterogeneous alloys are generated with various composition-contrasts between the two phases. After relaxing the as-generated structure, we compute its radial distribution function, and then we deduce by the Fourier transform technique its anomalous X-ray scattering pattern. Using a smoothing procedure, the computed X-ray scattering patterns are corrected for the termination errors due to the finite size of the model, allowing so a rigorous quantitative analysis of the anomalous small-angle scattering. Our simulation shows that, as expected, the anomalous small-angle X-ray scattering technique is a tool of choice for characterizing compositional heterogeneities coexisting with structural inhomogeneities in an amorphous alloy. Furthermore, the sizes of the compositional nanoheterogeneities, as measured by anomalous small-angle X-ray scattering technique, are X-ray energy independent. A quantitative analysis of the separated reduced anomalous small-angle X-ray scattering, as defined in this work, provided a good estimate of their size.

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

    PubMed

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

    2016-06-01

    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.

  16. 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.

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

    PubMed

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

    2016-06-01

    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. PMID:27370470

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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.

  20. Six-dimensional real and reciprocal space small-angle X-ray scattering tomography.

    PubMed

    Schaff, Florian; Bech, Martin; Zaslansky, Paul; Jud, Christoph; Liebi, Marianne; Guizar-Sicairos, Manuel; Pfeiffer, Franz

    2015-11-19

    When used in combination with raster scanning, small-angle X-ray scattering (SAXS) has proven to be a valuable imaging technique of the nanoscale, for example of bone, teeth and brain matter. Although two-dimensional projection imaging has been used to characterize various materials successfully, its three-dimensional extension, SAXS computed tomography, poses substantial challenges, which have yet to be overcome. Previous work using SAXS computed tomography was unable to preserve oriented SAXS signals during reconstruction. Here we present a solution to this problem and obtain a complete SAXS computed tomography, which preserves oriented scattering information. By introducing virtual tomography axes, we take advantage of the two-dimensional SAXS information recorded on an area detector and use it to reconstruct the full three-dimensional scattering distribution in reciprocal space for each voxel of the three-dimensional object in real space. The presented method could be of interest for a combined six-dimensional real and reciprocal space characterization of mesoscopic materials with hierarchically structured features with length scales ranging from a few nanometres to a few millimetres--for example, biomaterials such as bone or teeth, or functional materials such as fuel-cell or battery components.

  1. Six-dimensional real and reciprocal space small-angle X-ray scattering tomography

    NASA Astrophysics Data System (ADS)

    Schaff, Florian; Bech, Martin; Zaslansky, Paul; Jud, Christoph; Liebi, Marianne; Guizar-Sicairos, Manuel; Pfeiffer, Franz

    2015-11-01

    When used in combination with raster scanning, small-angle X-ray scattering (SAXS) has proven to be a valuable imaging technique of the nanoscale, for example of bone, teeth and brain matter. Although two-dimensional projection imaging has been used to characterize various materials successfully, its three-dimensional extension, SAXS computed tomography, poses substantial challenges, which have yet to be overcome. Previous work using SAXS computed tomography was unable to preserve oriented SAXS signals during reconstruction. Here we present a solution to this problem and obtain a complete SAXS computed tomography, which preserves oriented scattering information. By introducing virtual tomography axes, we take advantage of the two-dimensional SAXS information recorded on an area detector and use it to reconstruct the full three-dimensional scattering distribution in reciprocal space for each voxel of the three-dimensional object in real space. The presented method could be of interest for a combined six-dimensional real and reciprocal space characterization of mesoscopic materials with hierarchically structured features with length scales ranging from a few nanometres to a few millimetres—for example, biomaterials such as bone or teeth, or functional materials such as fuel-cell or battery components.

  2. Characterization of fullerenes and fullerene derivatives by small-angle neutron scattering and transmission measurements

    SciTech Connect

    Melnichenko, Y.B.; Wignall, G.D.; Affholter, K.A.

    1997-01-01

    Small-angle neutron scattering (SANS) has been shown to be an appropriate technique for the structural characterization of fullerenes (1) in solvents with strong SANS contrast (e.g. CS{sub 2}) and we have extended initial studies of C{sub 60} (1) to include C{sub 70} and C{sub 84} moieties. Deuterated solvents (e.g. toluene-d{sub 8}) have a high scattering length density (SLD), which is close to that of C{sub 60}, so there is virtually no SANS contrast with the solvent. Hence, these particles are practically {open_quotes}invisible{close_quotes} in such media, though the negative scattering length of hydrogen means that 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 and this paper describes the first results on cyclohexane-substituted fullerenes.

  3. Analyzing angle crashes at unsignalized intersections using machine learning techniques.

    PubMed

    Abdel-Aty, Mohamed; Haleem, Kirolos

    2011-01-01

    A recently developed machine learning technique, multivariate adaptive regression splines (MARS), is introduced in this study to predict vehicles' angle crashes. MARS has a promising prediction power, and does not suffer from interpretation complexity. Negative Binomial (NB) and MARS models were fitted and compared using extensive data collected on unsignalized intersections in Florida. Two models were estimated for angle crash frequency at 3- and 4-legged unsignalized intersections. Treating crash frequency as a continuous response variable for fitting a MARS model was also examined by considering the natural logarithm of the crash frequency. Finally, combining MARS with another machine learning technique (random forest) was explored and discussed. The fitted NB angle crash models showed several significant factors that contribute to angle crash occurrence at unsignalized intersections such as, traffic volume on the major road, the upstream distance to the nearest signalized intersection, the distance between successive unsignalized intersections, median type on the major approach, percentage of trucks on the major approach, size of the intersection and the geographic location within the state. Based on the mean square prediction error (MSPE) assessment criterion, MARS outperformed the corresponding NB models. Also, using MARS for predicting continuous response variables yielded more favorable results than predicting discrete response variables. The generated MARS models showed the most promising results after screening the covariates using random forest. Based on the results of this study, MARS is recommended as an efficient technique for predicting crashes at unsignalized intersections (angle crashes in this study).

  4. Design and use of a 6 meter neutron small-angle scattering spectrometer at KUR

    NASA Astrophysics Data System (ADS)

    Komura, S.; Takeda, T.; Fujii, H.; Osamura, K.; Mochiki, K.; Hasegawa, K.

    1983-05-01

    A 6 meter neutron small-angle scattering spectrometer has been constructed at the Kyoto University Reactor (KUR) and has been used successfully in various fields of application. The design principles and the characteristics of the spectrometer are described briefly. Some examples of the scattering measurements are presented.

  5. Broadband and Broad-Angle Low-Scattering Metasurface Based on Hybrid Optimization Algorithm

    PubMed Central

    Wang, Ke; Zhao, Jie; Cheng, Qiang; Dong, Di Sha; Cui, Tie Jun

    2014-01-01

    A broadband and broad-angle low-scattering metasurface is designed, fabricated, and characterized. Based on the optimization algorithm and far-field scattering pattern analysis, we propose a rapid and efficient method to design metasurfaces, which avoids the large amount of time-consuming electromagnetic simulations. Full-wave simulation and measurement results show that the proposed metasurface is insensitive to the polarization of incident waves, and presents good scattering-reduction properties for oblique incident waves. PMID:25089367

  6. 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.

  7. Counterion Distribution Around Protein-SNAs probed by Small-angle X-ray scattering

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Kurinji; Bedzyk, Michael; Kewalramani, Sumit; Moreau, Liane; Mirkin, Chad

    Protein-DNA conjugates couple the advanced cell transfection capabilities of spherical DNA architecture and the biocompatible enzymatic activity of a protein core to potentially create therapeutic agents with dual functionality. An understanding of their stabilizing ionic environment is crucial to better understand and predict their properties. Here, we use Small-angle X-ray scattering techniques to decipher the structure of the counterion cloud surrounding these DNA coated nanoparticles. Through the use of anomalous scattering techniques we have mapped the local concentrations of Rb+ ions in the region around the Protein-DNA constructs. These results are further corroborated with simulations using a geometric model for the excess charge density as function of radial distance from the protein core. Further, we investigate the influence of solution ionic strength on the structure of the DNA corona and demonstrate a reduction in the extension of the DNA corona with increasing concentration of NaCl in solution for the case of both single and double stranded DNA shells. Our work reveals the distribution of counterions in the vicinity of Protein-DNA conjugates and decouples the effect of solution ionic strength on the thickness of the DNA layer.

  8. Characterization of lysozyme adsorption in cellulosic chromatographic materials using small-angle neutron scattering.

    PubMed

    Koshari, Stijn H S; Wagner, Norman J; Lenhoff, Abraham M

    2015-06-19

    Measurements of the nanoscale structure of chromatographic adsorbents and the associated distribution of sorbed protein within the media can facilitate improvements in such media. We demonstrate a new technique for this purpose using small-angle neutron scattering (SANS) to characterize the nano- to microscale structure of the chromatographic media and sorbed protein under conditions relevant for preparative chromatographic separations. The adsorption of lysozyme on cellulosic S HyperCel™ (Pall Corporation), a strong cation exchanger, was investigated by SANS. The scattering spectrum is reduced to three contributions arising from (1) the chromatographic medium, (2) discrete protein molecules, and (3) the distribution of sorbed protein within the medium. These contributions are quantified for a range of protein loadings. The total concentration of protein in the chromatographic media can be quantified from the SANS spectrum and the protein is observed to retain its tertiary structure upon adsorption, within the resolution of the method. Further analysis of the SANS spectra shows that protein adsorption is uniform in the media. These measurement techniques provide new and valuable nanoscale information about protein sorption in chromatographic media.

  9. Angle-resolved spin wave band diagrams of square antidot lattices studied by Brillouin light scattering

    SciTech Connect

    Gubbiotti, G.; Tacchi, S.; Madami, M.; Carlotti, G.; Ding, J.; Adeyeye, A. O.

    2015-06-29

    The Brillouin light scattering technique has been exploited to study the angle-resolved spin wave band diagrams of squared Permalloy antidot lattice. Frequency dispersion of spin waves has been measured for a set of fixed wave vector magnitudes, while varying the wave vector in-plane orientation with respect to the applied magnetic field. The magnonic band gap between the two most dispersive modes exhibits a minimum value at an angular position, which exclusively depends on the product between the selected wave vector magnitude and the lattice constant of the array. The experimental data are in very good agreement with predictions obtained by dynamical matrix method calculations. The presented results are relevant for magnonic devices where the antidot lattice, acting as a diffraction grating, is exploited to achieve multidirectional spin wave emission.

  10. The crystallization of hectorite clays as monitored by small angle X-ray scattering and NMR

    SciTech Connect

    Carrado, K. A.; Xu, L.; Seifert, S.; Gregory, D.; Song, K.; Botto, R. E.

    1999-12-13

    The authors have probed the 48-hr crystallization of a magnesium silicate clay called hectorite. Small angle X-ray scattering (SAXS) at the Advanced Photon Source using aliquots ex situ has revealed that data is consistent with ex situ XRD, TGA, AFM, and IR data in that all these techniques see clay crystallite beginning to form in the first few hours of reaction. Tetraethylammonium (TEA) ions are used to aid crystallization and become incorporated as the exchange cations within the interlayers. {sup 13}C NMR shows that 80% of the final TEA loading is accomplished in the first 10 hrs. {sup 29}Si NMR displays a visible clay silicate peak after just 1 hr. In addition, the first in situ study of clay crystallization of any kind was performed by in situ SAXS. Results are consistent with the ex situ data as well as showing the sensitivity of SAXS to sol gel reactions occurring on the order of minutes.

  11. 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.

  12. 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.}

  13. 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.

  14. 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.

  15. Online ion-exchange chromatography for small-angle X-ray scattering

    PubMed Central

    Hutin, Stephanie; Brennich, Martha; Maillot, Benoit; Round, Adam

    2016-01-01

    Biological small-angle X-ray scattering (BioSAXS) is a powerful technique to determine the solution structure, particle size, shape and surface-to-volume ratio of macromolecules. However, a drawback is that the sample needs to be monodisperse. To ensure this, size-exclusion chromatography (SEC) has been implemented on many BioSAXS beamlines. Here, the integration of ion-exchange chromatography (IEC) using both continuous linear and step gradients on a beamline is described. Background subtraction for continuous gradients by shifting a reference measurement and two different approaches for step gradients, which are based on interpolating between two background measurements, are discussed. The results presented here serve as a proof of principle for online IEC and subsequent data treatment. PMID:27710930

  16. On the structure of concentrated detonation nanodiamond hydrosols with a positive ζ potential: Analysis of small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Avdeev, Mikhail V.; Tomchuk, Oleksandr V.; Ivankov, Oleksandr I.; Alexenskii, Alexander E.; Dideikin, Artur T.; Vul, Alexander Ya.

    2016-08-01

    Small-angle neutron scattering (SANS) was applied for the structure characterization of detonation nanodiamond (DND) aqueous suspensions with a positive ζ potential. The contrast variation technique (based on mixtures of light and heavy water) was used to study the structure of DND particles and their clusters in solutions. The results were compared with the data of the previous similar experiments for DND suspensions with a negative ζ potential. The experimental range of the neutron scattering contrast in the system was extended to maximally possible by starting with the initial concentrated suspensions separately prepared in light and heavy water.

  17. Measurement of energy spectra of small-angle scattering and distribution of optical microinhomogeneities in laser ceramics

    SciTech Connect

    Tverdokhleb, P E; Shepetkin, Yu A; Steinberg, I Sh; Belikov, A Yu; Vatnik, S M; Vedin, I A; Kurbatov, P F

    2014-06-30

    The energy spectra of small-angle light scattering from the samples of Nd:YAG ceramics and the spatial distributions of optical microinhomogeneities in them are measured. The spatial profiles of microinhomogeneities are found using the collinear heterodyne microprobe technique. Based on the obtained data, the comparison of noise and lasing characteristics of foreign and domestic samples of laser ceramics is carried out. (extreme light fields and their applications)

  18. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton

    NASA Astrophysics Data System (ADS)

    Fanelli, C.; Cisbani, E.; Hamilton, D. J.; Salmé, G.; Wojtsekhowski, B.; Ahmidouch, A.; Annand, J. R. M.; Baghdasaryan, H.; Beaufait, J.; Bosted, P.; Brash, E. J.; Butuceanu, C.; Carter, P.; Christy, E.; Chudakov, E.; Danagoulian, S.; Day, D.; Degtyarenko, P.; Ent, R.; Fenker, H.; Fowler, M.; Frlez, E.; Gaskell, D.; Gilman, R.; Horn, T.; Huber, G. M.; de Jager, C. W.; Jensen, E.; Jones, M. K.; Kelleher, A.; Keppel, C.; Khandaker, M.; Kohl, M.; Kumbartzki, G.; Lassiter, S.; Li, Y.; Lindgren, R.; Lovelace, H.; Luo, W.; Mack, D.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.; Maxwell, J.; Mbianda, G.; Meekins, D.; Meziane, M.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Mulholland, J.; Nelyubin, V.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Prok, Y.; Puckett, A. J. R.; Punjabi, V.; Shabestari, M.; Shahinyan, A.; Slifer, K.; Smith, G.; Solvignon, P.; Subedi, R.; Wesselmann, F. R.; Wood, S.; Ye, Z.; Zheng, X.

    2015-10-01

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70 ° . The longitudinal transfer KLL, measured to be 0.645 ±0.059 ±0.048 , where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ˜3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

  19. Hierarchical O(N) computation of small-angle scattering profiles and their associated derivatives

    PubMed Central

    Berlin, Konstantin; Gumerov, Nail A.; Fushman, David; Duraiswami, Ramani

    2014-01-01

    The need for fast approximate algorithms for Debye summation arises in computations performed in crystallography, small/wide-angle X-ray scattering and small-angle neutron scattering. When integrated into structure refinement protocols these algorithms can provide significant speed up over direct all-atom-to-all-atom computation. However, these protocols often employ an iterative gradient-based optimization procedure, which then requires derivatives of the profile with respect to atomic coordinates. This article presents an accurate, O(N) cost algorithm for the computation of scattering profile derivatives. The results reported here show orders of magnitude improvement in computational efficiency, while maintaining the prescribed accuracy. This opens the possibility to efficiently integrate small-angle scattering data into the structure determination and refinement of macromolecular systems. PMID:24701198

  20. Visibility measurements using two-angle forward scattering by liquid droplets.

    PubMed

    Peng, Peng; Li, Chengwei

    2016-05-20

    This study presents a two-angle forward scattering (TAFS) method that can be used to detect atmosphere visibility and distinguish different weather phenomena. The visibility measuring instrument has two receivers arranged at the forward scattering angles of 35° and 90°, and the atmosphere visibility is measured by the first receiver (35°). We use the ratio between the scattering phase functions P(35°) and P(90°) to judge the asymmetry parameter of atmospheric particles and to distinguish the weather phenomenon. Compared with multi-angle forward scattering (MAFS) that can distinguish fog, haze, and mist, TAFS can determine additional weather phenomena (i.e., normal weather and rain) and has fewer receivers. Thus, we improve the instrument design of this method whose visibility error is smaller than that of MAFS on rainy days. PMID:27411113

  1. 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.

  2. Energy-dispersive small-angle X-ray scattering with cone collimation using X-ray capillary optics

    NASA Astrophysics Data System (ADS)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi

    2016-09-01

    Energy-dispersive small-angle X-ray scattering (ED-SAXS) with an innovative design of cone collimation based on an ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL) had been explored. Using this new cone collimation system, scattering angle 2θ has a theoretical minimum angle related to the mean half-opening angle of the hollow cone beam of 1.42 mrad, and with the usable X-ray energy ranging from 4 to 30 keV, the resulting observable scattering vector q is down to a minimum value of about 0.003 Å-1 (or a Bragg spacing of about 2100 Å). However, the absorption of lower energies by X-ray capillary optics, sample transmission, and detector response function limits the application range to lower energy. Cone collimation ED-SAXS experiments carried out on pure water, Lupolen, and in situ temperature-dependent measurement of diacetylenic acid/melamine micelle solid were presented at three different scattering angles 2θ of 0.18°, 0.70° and 1.18° to illustrate the new opportunities offered by this technique as well as its limitations. Also, a comparison has been made by replacing the PPXRL with a pinhole, and the result shows that cone collimation ED-SAXS based on ESBC with PPXRL was helpful in improving the signal-to-noise ratio (i.e., reducing the parasitic background scattering) than ESBC with a pinhole. The cone collimation instrument based on X-ray capillary optics could be considered as a promising tool to perform SAXS experiments, especially cone collimation ED-SAXS has potential application for the in situ temperature-dependent studying on the kinetics of phase transitions.

  3. Phospholipid Membrane Protection by Sugar Molecules during Dehydration-Insights into Molecular Mechanisms Using Scattering Techniques

    SciTech Connect

    Garvey, Christopher J.; Lenné, Thomas; Koster, Karen L.; Kent, Ben; Bryant, Gary

    2014-09-24

    Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol) can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS) and synchrotron-based X-ray scattering (small angle (SAXS) and wide angle (WAXS)) can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids.

  4. 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

  5. Angle-Resolved Second-Harmonic Light Scattering from Colloidal Particles

    NASA Astrophysics Data System (ADS)

    Yang, N.; Angerer, W. E.; Yodh, A. G.

    2001-09-01

    We report angle-resolved second-harmonic generation (SHG) measurements from suspensions of centrosymmetric micron-size polystyrene spheres with surface-adsorbed dye (malachite green). The second-harmonic scattering profiles differ qualitatively from linear light scattering profiles of the same particles. We investigated these radiation patterns using several polarization configurations and particle diameters. We introduce a simple Rayleigh-Gans-Debye model to account for the SHG scattering anisotropy. The model compares favorably with our experimental data. Our measurements suggest scattering anisotropy may be used to isolate particle nonlinear optics from other bulk nonlinear optical effects in suspension.

  6. Angle-Resolved Second-Harmonic Light Scattering from Colloidal Particles

    SciTech Connect

    Yang, N.; Angerer, W. E.; Yodh, A. G.

    2001-09-03

    We report angle-resolved second-harmonic generation (SHG) measurements from suspensions of centrosymmetric micron-size polystyrene spheres with surface-adsorbed dye (malachite green). The second-harmonic scattering profiles differ qualitatively from linear light scattering profiles of the same particles. We investigated these radiation patterns using several polarization configurations and particle diameters. We introduce a simple Rayleigh-Gans-Debye model to account for the SHG scattering anisotropy. The model compares favorably with our experimental data. Our measurements suggest scattering anisotropy may be used to isolate particle nonlinear optics from other bulk nonlinear optical effects in suspension.

  7. The optical scattering property: spatial and angle variability in Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Li, Cai; Cao, Wenxi; Yang, Yuezhong; Xu, Zhantang

    2015-02-01

    Observations are presented of the Volume scattering function (VSF) over the angular interval 20 to 160°, to maximum depth of about 90m in the Northern South China Sea in Case I and Case II waters. The observations were collected by using a self-developed in situ scattering instrument, which synchronously measured the attenuation coefficient, the VSFs in seven angles between 20 to 160° at 650nm, and the sea depths. General, the VSFs show a strong scattering in the forward, a broad scattering minimum in the scattering angular interval 90 to 126° and a weak increase in the rest of backward scattering angles. The analysis of the in situ data also indicates that the magnitude and the shape of the VSF change with areas and profile depths. From Case II to Case I, the forward scattering in 20°, which is mainly due to relatively large suspended particles, varied about three orders magnitude with highest values observed in Case II waters. In Case I waters, form the surface layer to the deeper layer, the magnitude of the VSFs firstly decreased with the depth, and then increased with the depth until reached a maximum scattering layer between 30 to 50m, and then decreased with depth until reached the maximum measurement depth. In Case II waters, the vertical profile distributions of VSF are complex, but in almost all profile, the magnitude of the VSFs firstly decreased with the depth, and then increased with the depth until reached the maximum measurement depth. The result of analysis also showed that in almost all of these stations, in the surface water, based on the light scattering by bubbles at shallow depths, the angle scattering at 60º-80º has a significant "shoulder", and the wind plays a key role in the bubble scattering.

  8. 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.

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

    PubMed Central

    Mitropoulos, Athanasios Ch.; Favvas, Evangelos P.; Stefanopoulos, Konstantinos L.; Vansant, Etienne F.

    2016-01-01

    Everett’s theorem-6 of the domain theory was examined by conducting adsorption in situ with small angle x-ray scattering (SAXS) supplemented by the contrast matching technique. The study focuses on the spectrum differences of a point to which the system arrives from different scanning paths. It is noted that according to this theorem at a common point the system has similar macroscopic properties. Furthermore it was examined the memory string of the system. We concluded that opposite to theorem-6: a) at a common point the system can reach in a finite (not an infinite) number of ways, b) a correction for the thickness of the adsorbed film prior to capillary condensation is necessary, and c) the scattering curves although at high-Q values coincide, at low-Q values are different indicating different microscopic states. That is, at a common point the system holds different metastable states sustained by hysteresis effects. These metastable states are the ones which highlight the way of a system back to a return point memory (RPM). Entering the hysteresis loop from different RPMs different histories are implanted to the paths toward the common point. Although in general the memory points refer to relaxation phenomena, they also constitute a characteristic feature of capillary condensation. Analogies of the no-passing rule and the adiabaticity assumption in the frame of adsorption hysteresis are discussed. PMID:27741263

  10. Synchrotron-based small-angle X-ray scattering (SAXS) of proteins in solution

    PubMed Central

    Skou, Soren; Gillilan, Richard E

    2015-01-01

    Summary With recent advances in data analysis algorithms, X-ray detectors, and synchrotron sources, small-angle X-ray scattering (SAXS) has become much more accessible to the structural biology community than ever before. Although limited to ~10 Å resolution, SAXS can provide a wealth of structural information on biomolecules in solution and is compatible with a wide range of experimental conditions. SAXS is thus an attractive alternative when crystallography is not possible. Moreover, advanced usage of SAXS can provide unique insight into biomolecular behavior that can only be observed in solution, such as large conformational changes and transient protein-protein interactions. Unlike crystal diffraction data, however, solution scattering data are subtle in appearance, highly sensitive to sample quality and experimental errors, and easily misinterpreted. In addition, synchrotron beamlines that are dedicated to SAXS are often unfamiliar to the non-specialist. Here, we present a series of procedures that can be used for SAXS data collection and basic cross-checks designed to detect and avoid aggregation, concentration effects, radiation damage, buffer mismatch, and other common problems. The protein, human serum albumin (HSA), serves as a convenient and easily replicated example of just how subtle these problems can sometimes be, but also of how proper technique can yield pristine data even in problematic cases. Because typical data collection times at a synchrotron are only one to several days, we recommend that the sample purity, homogeneity, and solubility be extensively optimized prior to the experiment. PMID:24967622

  11. The dynamic duo: Combining NMR and small angle scattering in structural biology

    PubMed Central

    Hennig, Janosch; Sattler, Michael

    2014-01-01

    Structural biology provides essential information for elucidating molecular mechanisms that underlie biological function. Advances in hardware, sample preparation, experimental methods, and computational approaches now enable structural analysis of protein complexes with increasing complexity that more closely represent biologically entities in the cellular environment. Integrated multidisciplinary approaches are required to overcome limitations of individual methods and take advantage of complementary aspects provided by different structural biology techniques. Although X-ray crystallography remains the method of choice for structural analysis of large complexes, crystallization of flexible systems is often difficult and does typically not provide insights into conformational dynamics present in solution. Nuclear magnetic resonance spectroscopy (NMR) is well-suited to study dynamics at picosecond to second time scales, and to map binding interfaces even of large systems at residue resolution but suffers from poor sensitivity with increasing molecular weight. Small angle scattering (SAS) methods provide low resolution information in solution and can characterize dynamics and conformational equilibria complementary to crystallography and NMR. The combination of NMR, crystallography, and SAS is, thus, very useful for analysis of the structure and conformational dynamics of (large) protein complexes in solution. In high molecular weight systems, where NMR data are often sparse, SAS provides additional structural information and can differentiate between NMR-derived models. Scattering data can also validate the solution conformation of a crystal structure and indicate the presence of conformational equilibria. Here, we review current state-of-the-art approaches for combining NMR, crystallography, and SAS data to characterize protein complexes in solution. PMID:24687405

  12. Application of electrically invisible antennas to the modulated scatterer technique

    NASA Astrophysics Data System (ADS)

    Crocker, Dylan Andrew

    The Modulated Scatterer Technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers consist of dipole antennas centrally loaded with a lumped element capable of modulation (commonly a PIN diode). By modulating the load element, the signal scattered from the MST scatterer is also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the modulation depth of scatterers commonly used in MST, the concept of electrically invisible antennas is applied to the design of these scatterers and is the focus of this work. Electrical invisibility of linear antennas, such as loaded dipoles, can be achieved by loading a scatterer in such a way that, when illuminated by an electromagnetic wave, the integral of the current induced along the length of the scatterer (and hence the scattered field as well) approaches zero. By designing a scatterer to be capable of modulation between visible (scattering) and invisible (minimum scattering) states, the modulation depth may be improved. This thesis presents simulations and measurements of new MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (i.e., a PIN diode). Further, the scattering during the forward bias state remains the same as that of a traditional MST scatterer, resulting in an increase in modulation depth. This new MST scatterer design technique may also have application in improving the performance of similar sensors such as radio frequency identification (RFID) tags.

  13. Enhanced small-angle scattering connected to the Widom line in simulations of supercooled water

    NASA Astrophysics Data System (ADS)

    Wikfeldt, K. T.; Huang, C.; Nilsson, A.; Pettersson, L. G. M.

    2011-06-01

    We present extensive simulations on the TIP4P/2005 water model showing significantly enhanced small-angle scattering (SAS) in the supercooled regime. The SAS is related to the presence of a Widom line (TW) characterized by maxima in thermodynamic response functions and Ornstein-Zernike correlation length. Recent experimental small-angle x-ray scattering data [Huang et al., J. Chem. Phys. 133, 134504 (2010)], 10.1063/1.3495974 are excellently reproduced, albeit with an increasing temperature offset at lower temperatures. Assuming the same origin of the SAS in experiment and model this suggests the existence of a Widom line also in real supercooled water. Simulations performed at 1000 bar show an increased abruptness of a crossover from dominating high-density (HDL) to dominating low-density (LDL) liquid and strongly enhanced SAS associated with crossing TW, consistent with a recent determination of the critical pressure of TIP4P/2005 at 1350 bar. Furthermore, good agreement with experimental isothermal compressibilities at 1000, 1500, and 2000 bar shows that the high pressure supercooled thermodynamic behavior of water is well described by TIP4P/2005. Analysis of the tetrahedrality parameter Q reveals that the HDL-LDL structural transition is very sharp at 1000 bar, and that structural fluctuations become strongly coupled to density fluctuations upon approaching TW. Furthermore, the tetrahedrality distribution becomes bimodal at ambient temperatures, an observation that possibly provides a link between HDL-LDL fluctuations and the structural bimodality in liquid water indicated by x-ray spectroscopic techniques. Computed x-ray absorption spectra are indeed found to show sensitivity to the tetrahedrality parameter.

  14. Initial State Helicity Correlation in Wide Angle Compton Scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Jixie; Day, Donal; Keller, Dustin; Rondon, Oscar

    2014-09-01

    The applicability of pQCD to exclusive reactions at medium energies is a subject of considerable interest. Real Compton scattering (RCS) has the potential to provide insight to this unsettled issue. In pQCD, three active quarks and two hard gluons are involved when describing RCS. But the cross sections do not agree with the pQCD predictions. In contrast, a handbag dominance model, involving only one single quark coupling to the spectator through generalized parton distributions (GPDs) does a good job of matching the cross section data. A measurement of the longitudinal polarization transfer parameter KLL was found inconsistent with predictions of pQCD yet consistent with calculations within the hand-bag mechanism. Further Miller's handbag approach, which including quark and hadron helicity flip, contradicts pQCD and others which demands that KLL =ALL , the initial state helicity correlation asymmetry, by finding that KLL ≠ALL . The first ever measurement of ALL has been proposed to run in Jefferson Lab's Hall C. This experiment will utilize an untagged bremsstrahlung photon beam and the longitudinally polarized UVA/JLAB proton target. After a brief introduction to the physics, the experiment will be described and the expected results presented.

  15. On the role of block copolymer additives for calcium carbonate crystallization: small angle neutron scattering investigation by applying contrast variation.

    PubMed

    Endo, Hitoshi; Schwahn, Dietmar; Cölfen, Helmut

    2004-05-15

    The role of the double-hydrophilic block copolymer poly(ethylen glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) on the morphogenesis of calcium carbonate (CaCO3) was studied by applying the contrast variation small angle neutron scattering technique. The morphology and size of CaCO3 crystals is strongly affected by the addition of PEG-b-PMAA. In order to determine the partial scattering functions of the polymer and CaCO3 mineral, we developed both an experimental and theoretical approach with a sophisticated method of their determination from the scattering intensity. Partial scattering functions give detailed information for each component. In particular, the partial scattering function of the polymer, Spp, shows a monotonic slope with Q(-2 to -3) where the scattering vector Q is low (Q < 0.01 Angstrom(-1)), which is a clear evidence that the polymer within the CaCO3 mineral has a mass fractal dimension. The other partial scattering functions reflected the geometry of the CaCO3 particles or the "interaction" of polymer and CaCO3 on a microscopic scale, which leads to a coherent view with Spp.

  16. Noctilucent cloud polarimetry: Twilight measurements in a wide range of scattering angles

    NASA Astrophysics Data System (ADS)

    Ugolnikov, Oleg S.; Maslov, Igor A.; Kozelov, Boris V.; Dlugach, Janna M.

    2016-06-01

    Wide-field polarization measurements of the twilight sky background during several nights with bright and extended noctilucent clouds in central and northern Russia in 2014 and 2015 are used to build the phase dependence of the degree of polarization of sunlight scattered by cloud particles in a wide range of scattering angles (from 40° to 130°). This range covers the linear polarization maximum near 90° and large-angle slope of the curve. The polarization in this angle range is most sensitive to the particle size. The method of separation of scattering on cloud particles from the twilight background is presented. Results are compared with T-matrix simulations for different sizes and shapes of ice particles; the best-fit model radius of particles (0.06 μm) and maximum radius (about 0.1 μm) are estimated.

  17. Improving gated cardiac scanning using limited-angle reconstruction technique

    SciTech Connect

    Tam, K.C.; Perez-Mendez, V.

    1983-02-01

    Selected phases of the cardiac cycle can be imaged by the method of gated cardiac scanning using whole body scanners. However, since there is no synchronization between the random heart beats and the CT machine, the output will have gaps in the angular coverage of each scan. The missing projections in these gaps result in artifacts in the reconstructed images. In this paper, the technique of limited-angle reconstruction is employed to fill in the missing projections to remove the artifacts. The object is transformed back and forth between the object space and the projection space, being corrected in each step by the constraints of the finite spatial extent and of the upper and lower bounds of the object in the object space, and the known projections in the projection space. It is found that by using the proposed algorithm the rms errors of the limited-angle images are reduced to a level comparable to those of the complete-angle images. The same iteration algorithm can also be used to reduce the fan beam scanning angle from 360 degree to 180 degree without sacrificing much image quality.

  18. 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

  19. Wave scattering from a periodic dielectric surface for a general angle of incidence

    NASA Technical Reports Server (NTRS)

    Chuang, S. L.; Kong, J. A.

    1982-01-01

    Electromagnetic waves scattered from a periodic dielectric and perfectly conducting surface are studied for a general angle of incidence. It is shown that the one-dimensional corrugated surface can be solved by using two scalar functions: the components of the electric and magnetic fields along the row direction of the surface, and appropriate boundary conditions to obtain simple matrix equations. Results are compared to the case where the incident angle wave vector is perpendicular to the row direction. Numerical results demonstrate that energy conservation and reciprocity are obeyed for scattering by sinusoidal surfaces for the general case, which checks the consistency of the formalism.

  20. Irena : tool suite for modeling and analysis of small-angle scattering.

    SciTech Connect

    Ilavsky, J.; Jemian, P.

    2009-04-01

    Irena, a tool suite for analysis of both X-ray and neutron small-angle scattering (SAS) data within the commercial Igor Pro application, brings together a comprehensive suite of tools useful for investigations in materials science, physics, chemistry, polymer science and other fields. In addition to Guinier and Porod fits, the suite combines a variety of advanced SAS data evaluation tools for the modeling of size distribution in the dilute limit using maximum entropy and other methods, dilute limit small-angle scattering from multiple non-interacting populations of scatterers, the pair-distance distribution function, a unified fit, the Debye-Bueche model, the reflectivity (X-ray and neutron) using Parratt's formalism, and small-angle diffraction. There are also a number of support tools, such as a data import/export tool supporting a broad sampling of common data formats, a data modification tool, a presentation-quality graphics tool optimized for small-angle scattering data, and a neutron and X-ray scattering contrast calculator. These tools are brought together into one suite with consistent interfaces and functionality. The suite allows robust automated note recording and saving of parameters during export.

  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. Small-angle x-ray scattering of intercalation compounds of graphite, fluorographite, and graphite oxide

    SciTech Connect

    Perevozkin, V.Yu.; Yur'ev, G.S.; Nazarov, A.S.; Danilenko, A.M.; Lisitsa, V.V.; Makotchenko, V.G.; Paasonen, V.M.; Yakovlev, I.I.

    1988-05-01

    Graphite intercalation compounds are interesting as cathode materials in chemical current sources and catalysts and are good conductors of electricity. Small-angle x-ray scattering was studied on natural graphite, intercalation compounds of fluorinated graphite, graphite oxide, and the products of reduction of the compounds. It was shown that scattering takes place in regions with a lower density and the size of the density inhomogeneities was determined.

  3. A 6-Meter Neutron Small-Angle Scattering Spectrometer at KUR

    NASA Astrophysics Data System (ADS)

    Komura, Shigehiro; Takeda, Takayoshi; Fujii, Hironobu; Toyoshima, Yoshinori; Osamura, Kozo; Mochiki, Koichi; Hasegawa, Ken'ichi

    1983-02-01

    A 6-meter neutron small-angle scattering spectrometer has been constructed at Kyoto University Reactor (KUR) and has been used successfully for various fields of application in these three years. This paper describes overall design principles and the characteristics of the various parts of the spectrometers which can be assembled and disassembled easily at KUR. Some examples of scattering measurements are presented to show the performance of the spectrometer.

  4. Effect of the concentration of inhomogeneities on the multiple small-angle neutron scattering

    SciTech Connect

    Abov, Yu. G.; Dzheparov, F. S.; Elyutin, N. O.; Lvov, D. V. Tyulyusov, A. N.

    2013-03-15

    The interference effects manifested during multiple small-angle neutron scattering (MSANS) on a chaotically arranged close-packed ensemble of scatterers have been studied. MSANS measurements have been performed for mixtures of Al and Ti-Zr alloy powders. It is shown that the results can be satisfactorily described based on a theory that takes into account spatial correlations in the arrangement of powder grains.

  5. Far-ultraviolet studies. III - A search for light scattered at large angles by dust

    NASA Technical Reports Server (NTRS)

    Henry, R. C.; Anderson, R.; Feldman, P. D.; Fastie, W. G.

    1978-01-01

    The Apollo 17 far-ultraviolet spectrometer was used during trans-earth coast to measure the brightness of two regions at moderate galactic latitudes. The signal obtained can be entirely accounted for by light from stars in the field of view, with no contribution from galactic-plane starlight scattered off interstellar dust. It is concluded that the interstellar grains are extremely poor large-angle scatterers in the far-ultraviolet.

  6. Spin waves in full-polarized state of Dzyaloshinskii-Moriya helimagnets: Small-angle neutron scattering study

    NASA Astrophysics Data System (ADS)

    Grigoriev, S. V.; Sukhanov, A. S.; Altynbaev, E. V.; Siegfried, S.-A.; Heinemann, A.; Kizhe, P.; Maleyev, S. V.

    2015-12-01

    We develop the technique to study the spin-wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin-waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centered at the momentum transfer corresponding to the helix wave vector in helimagnetic phase ks, which is oriented along the applied magnetic field H . The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness A for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature Tc.

  7. Relationship of Light Scattering at an Angle in the Backward Direction to the Backscattering Coefficient

    NASA Astrophysics Data System (ADS)

    Boss, Emmanuel; Pegau, W. Scott

    2001-10-01

    We revisit the problem of computing the backscattering coefficient based on the measurement of scattering at one angle in the back direction. Our approach uses theory and new observations of the volume scattering function (VSF) to evaluate the choice of angle used to estimate bb . We add to previous studies by explicitly treating the molecular backscattering of water (bbw ) and its contribution to the VSF shape and to bb . We find that there are two reasons for the tight correlation between observed scattering near 120 and the backscattering coefficient reported by Oishi [Appl. Opt. 29, 4658, (1990) , namely, that (1) the shape] of the VSF of particles (normalized to the backscattering) does not vary much near that angle for particle assemblages of differing optical properties and size, and (2) the ratio of the VSF to the backscattering is not sensitive to the contribution by water near this angle. We provide a method to correct for the water contribution to backscattering when single-angle measurements are used in the back direction (for angles spanning from near 90 to 160 ) that should provide improved estimates of the backscattering coefficient.

  8. The accurate assessment of small-angle X-ray scattering data

    SciTech Connect

    Grant, Thomas D.; Luft, Joseph R.; Carter, Lester G.; Matsui, Tsutomu; Weiss, Thomas M.; Martel, Anne; Snell, Edward H.

    2015-01-01

    A set of quantitative techniques is suggested for assessing SAXS data quality. These are applied in the form of a script, SAXStats, to a test set of 27 proteins, showing that these techniques are more sensitive than manual assessment of data quality. Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targets for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. The studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality.

  9. The measurement and modelling of light scattering by phytoplankton cells at narrow forward angles

    NASA Astrophysics Data System (ADS)

    MacCallum, Iain; Cunningham, Alex; McKee, David

    2004-07-01

    A procedure has been devised for measuring the angular dependence of light scattering from suspensions of phytoplankton cells at forward angles from 0.25° to 8°. The cells were illuminated with a spatially-filtered laser beam and the angular distribution of scattered light measured by tracking a photodetector across the Fourier plane of a collecting lens using a stepper-motor driven stage. The procedure was calibrated by measuring scattering from latex bead suspensions with known size distributions. It was then used to examine the scattering from cultures of the unicellular algae Isochrysis galbana (4 µm × 5 µm), Dunaliella primolecta (6 µm × 7 µm) and Rhinomonas reticulata (5 µm × 11 µm). The results were compared with the predictions of Mie theory. Excellent agreement was obtained for spherical particles. A suitable choice of spherical-equivalent scattering parameters was required to enable reasonable agreement within the first diffraction lobe for ellipsoidal particles.

  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. Small-angle x-ray scattering study of crazing in bulk thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Salomons, Gregory John

    Crazing is a form of tension-induced deformation consisting of microscopic cracks spanned by load-bearing fibrils. This is generally considered to be the primary source of plastic strain response of rubber-modified thermoplastics subjected to applied tensile stress. An understanding of the mechanisms involved in crazing is, therefore, valuable as a means of identifying structure-property relationships. Extensive studies on single crazes in thin films have been done,sp{1-6} however, experiments on crazing in bulk materials have been fraught with problems, such as difficulties with the production of uniform crazes and accurate temperature control.sp7 A new apparatus has been designed to overcome many of these problems; a symmetric tensile stretching mechanism and a radiant heating technique combined with real-time small-angle x-ray scattering (RTSAXS) is used to examine craze fibril structure. The analysis of small-angle x-ray scattering (SAXS) data is highly model-dependent requiring precise structural models to ensure accurate interpretation. Recently, improved measurement techniques have called into question some aspects of the long accepted models applied to SAXS interpretation of craze structures.sp{8,9} A detailed examination of the models applicable to craze fibril structure is presented here, including a newly proposed model involving power-law density distributions within the fibrils. It is shown that the best description of craze fibrils comes from a Gaussian density distribution. This is in contrast to the traditional models which describe the fibrils as having uniform density with sharp boundaries.sp{1,2} RTSAXS studies of High Impact Polystyrene (HIPS) and Polystyrene (PS) blended with 2 wt.% Polybutadiene (PB) were performed using a constant strain rate of 5 × 10sp{-4} ssp{-1} and temperatures from 30 to 70sp°C. Crazing deformation modes were identified and the macroscopic deformation characteristics for the two materials were compared revealing a

  12. 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.

  13. Structure of unilamellar vesicles: Numerical analysis based on small-angle neutron scattering data

    SciTech Connect

    Zemlyanaya, E. V. Kiselev, M. A.; Zbytovska, J.; Almasy, L.; Aswal, V. K.; Strunz, P.; Wartewig, S.; Neubert, R.

    2006-12-15

    The structure of polydispersed populations of unilamellar vesicles is studied by small-angle neutron scattering for three types of lipid systems, namely, single-, two-and four-component vesicular systems. Results of the numerical analysis based on the separated-form-factor model are reported.

  14. Application of electrically invisible antennas to the Modulated Scatterer Technique

    SciTech Connect

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. Our paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).

  15. Application of electrically invisible antennas to the Modulated Scatterer Technique

    DOE PAGES

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve themore » MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. Our paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).« less

  16. Application of electrically invisible antennas to the modulated scatterer technique

    SciTech Connect

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. This paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).

  17. Application of electrically invisible antennas to the modulated scatterer technique

    DOE PAGES

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve themore » MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. This paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).« less

  18. 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)

  19. Polarization transfer in wide-angle Compton scattering and single-pion photoproduction from the proton

    DOE PAGES

    Fanelli, Cristiano V.

    2015-10-06

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θPcm = 70°. The longitudinal transfer KLL, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.more » However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.« less

  20. Polarization transfer in wide-angle Compton scattering and single-pion photoproduction from the proton

    SciTech Connect

    Fanelli, Cristiano V.

    2015-10-06

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θPcm = 70°. The longitudinal transfer KLL, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

  1. 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

  2. Pitch angle scattering of an energetic magnetized particle by a circularly polarized electromagnetic wave

    SciTech Connect

    Bellan, P. M.

    2013-04-15

    The interaction between a circularly polarized wave and an energetic gyrating particle is described using a relativistic pseudo-potential that is a function of the frequency mismatch. Analysis of the pseudo-potential provides a means for interpreting numerical results. The pseudo-potential profile depends on the initial mismatch, the normalized wave amplitude, and the initial angle between the wave magnetic field and the particle perpendicular velocity. For zero initial mismatch, the pseudo-potential consists of only one valley, but for finite mismatch, there can be two valleys separated by a hill. A large pitch angle scattering of the energetic electron can occur in the two-valley situation but fast scattering can also occur in a single valley. Examples relevant to magnetospheric whistler waves show that the energetic electron pitch angle can be deflected 5 Degree-Sign towards the loss cone when transiting a 10 ms long coherent wave packet having realistic parameters.

  3. Small angle x-ray scattering with a beryllium compound refractive lens as focusing optic

    SciTech Connect

    Timmann, Andreas; Doehrmann, Ralph; Schubert, Tom; Schulte-Schrepping, Horst; Hahn, Ulrich; Kuhlmann, Marion; Gehrke, Rainer; Roth, Stephan Volkher; Schropp, Andreas; Schroer, Christian; Lengeler, Bruno

    2009-04-15

    At BW4 at HASYLAB a beryllium compound refractive lens (Be-CRL) is used for the focusing in small-angle x-ray scattering experiments. Using it provides the advantages of higher long-term stability and a much easier alignment compared to a setup with focusing mirrors. In our investigations presented here, we show the advantages of using a Be-CRL in small-angle and also ultra small-angle x-ray scattering. We investigated the beam characteristics at the sample position with respect to spot size and photon flux. The spot size is comparable to that of a setup with focusing mirrors but with a gain in flux and better long-term stability. It is also shown that plane mirrors are still necessary to suppress higher order energies passing the monochromator.

  4. Unbalance identification using the least angle regression technique

    NASA Astrophysics Data System (ADS)

    Chatzisavvas, Ioannis; Dohnal, Fadi

    2015-01-01

    The present investigation proposes a robust procedure for unbalance identification using the equivalent load method based on sparse vibration measurements. The procedure is demonstrated and benchmarked on an example rotor at constant speed. Since the number of measuring positions is much smaller than the number of possible fault locations, performing unbalance identification leads to an ill-posed problem. This problem was tried to be overcome previously with modal expansion in the time domain and with several linear regressions in the frequency domain. However, since the solution to the problem is a sparse equivalent force vector, these methods cannot provide a robust identification procedure. A robust identification can only be achieved by providing a-priori information on the number of unbalances to be identified. The presently proposed procedure achieves more precise unbalance identification without the need of a-priori information by incorporating a regularization technique. A well-known technique for producing sparse solutions is the Least Absolute Shrinkage and Selection Operator (LASSO). The proposed procedure is based on the generalized technique Least Angle Regression (LAR) which finds all the solutions of LASSO. A comparison of the time-domain approach, the frequency-domain approach and the proposed technique is made and the superiority of the latter technique in identifying the number of possible fault locations is highlighted. The selection of the threshold of the convergence algorithm of LAR as well as the selection of the value of the Lagrangian multiplier is discussed in some detail.

  5. 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.

  6. Nano-Scale Morphology of Melanosomes Revealed by Small-Angle X-Ray Scattering

    PubMed Central

    Gorniak, Thomas; Haraszti, Tamas; Garamus, Vasyl M.; Buck, Andreas R.; Senkbeil, Tobias; Priebe, Marius; Hedberg-Buenz, Adam; Koehn, Demelza; Salditt, Tim; Grunze, Michael; Anderson, Michael G.; Rosenhahn, Axel

    2014-01-01

    Melanosomes are highly specialized organelles that produce and store the pigment melanin, thereby fulfilling essential functions within their host organism. Besides having obvious cosmetic consequences – determining the color of skin, hair and the iris – they contribute to photochemical protection from ultraviolet radiation, as well as to vision (by defining how much light enters the eye). Though melanosomes can be beneficial for health, abnormalities in their structure can lead to adverse effects. Knowledge of their ultrastructure will be crucial to gaining insight into the mechanisms that ultimately lead to melanosome-related diseases. However, due to their small size and electron-dense content, physiologically intact melanosomes are recalcitrant to study by common imaging techniques such as light and transmission electron microscopy. In contrast, X-ray-based methodologies offer both high spatial resolution and powerful penetrating capabilities, and thus are well suited to study the ultrastructure of electron-dense organelles in their natural, hydrated form. Here, we report on the application of small-angle X-ray scattering – a method effective in determining the three-dimensional structures of biomolecules – to whole, hydrated murine melanosomes. The use of complementary information from the scattering signal of a large ensemble of suspended organelles and from single, vitrified specimens revealed a melanosomal sub-structure whose surface and bulk properties differ in two commonly used inbred strains of laboratory mice. Whereas melanosomes in C57BL/6J mice have a well-defined surface and are densely packed with 40-nm units, their counterparts in DBA/2J mice feature a rough surface, are more granular and consist of 60-nm building blocks. The fact that these strains have different coat colors and distinct susceptibilities to pigment-related eye disease suggest that these differences in size and packing are of biological significance. PMID:24621581

  7. 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.

  8. Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering in Outer RB

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2007-01-01

    We present the equatorial and bounce average pitch angle diffusion coefficients for scattering of relativistic electrons by the H+ mode of EMIC waves. Both the model (prescribed) and self consistent distributions over the wave normal angle are considered. The main results of our calculation can be summarized as follows: First, in comparison with field aligned waves, the intermediate and highly oblique waves reduce the pitch angle range subject to diffusion, and strongly suppress the scattering rate for low energy electrons (E less than 2 MeV). Second, for electron energies greater than 5 MeV, the |n| = 1 resonances operate only in a narrow region at large pitch-angles, and despite their greatest contribution in case of field aligned waves, cannot cause electron diffusion into the loss cone. For those energies, oblique waves at |n| greater than 1 resonances are more effective, extending the range of pitch angle diffusion down to the loss cone boundary, and increasing diffusion at small pitch angles by orders of magnitude.

  9. Methods for analysis of size-exclusion chromatography–small-angle X-ray scattering and reconstruction of protein scattering

    PubMed Central

    Malaby, Andrew W.; Chakravarthy, Srinivas; Irving, Thomas C.; Kathuria, Sagar V.; Bilsel, Osman; Lambright, David G.

    2015-01-01

    Size-exclusion chromatography in line with small-angle X-ray scattering (SEC–SAXS) has emerged as an important method for investigation of heterogeneous and self-associating systems, but presents specific challenges for data processing including buffer subtraction and analysis of overlapping peaks. This paper presents novel methods based on singular value decomposition (SVD) and Guinier-optimized linear combination (LC) to facilitate analysis of SEC–SAXS data sets and high-quality reconstruction of protein scattering directly from peak regions. It is shown that Guinier-optimized buffer subtraction can reduce common subtraction artifacts and that Guinier-optimized linear combination of significant SVD basis components improves signal-to-noise and allows reconstruction of protein scattering, even in the absence of matching buffer regions. In test cases with conventional SAXS data sets for cytochrome c and SEC–SAXS data sets for the small GTPase Arf6 and the Arf GTPase exchange factors Grp1 and cytohesin-1, SVD–LC consistently provided higher quality reconstruction of protein scattering than either direct or Guinier-optimized buffer subtraction. These methods have been implemented in the context of a Python-extensible Mac OS X application known as Data Evaluation and Likelihood Analysis (DELA), which provides convenient tools for data-set selection, beam intensity normalization, SVD, and other relevant processing and analytical procedures, as well as automated Python scripts for common SAXS analyses and Guinier-optimized reconstruction of protein scattering. PMID:26306089

  10. 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

  11. Note: A gel based imaging technique of the iridocorneal angle for evaluation of angle-closure glaucoma

    NASA Astrophysics Data System (ADS)

    Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, T.

    2014-06-01

    Noninvasive medical imaging techniques have high potential in the field of ocular imaging research. Angle closure glaucoma is a major disease causing blindness and a possible way of detection is the examination of the anterior chamber angle in eyes. Here, a simple optical method for the evaluation of angle-closure glaucoma is proposed and illustrated. The light propagation from the region associated with the iridocorneal angle to the exterior of eye is considered analytically. The design of the gel assisted probe prototype is carried out and the imaging of iridocorneal angle is performed on an eye model.

  12. Structural modeling of proteins by integrating small-angle x-ray scattering data

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-Hui; Peng, Jun-Hui; Zhang, Zhi-Yong

    2015-12-01

    Elucidating the structure of large biomolecules such as multi-domain proteins or protein complexes is challenging due to their high flexibility in solution. Recently, an “integrative structural biology” approach has been proposed, which aims to determine the protein structure and characterize protein flexibility by combining complementary high- and low-resolution experimental data using computer simulations. Small-angle x-ray scattering (SAXS) is an efficient technique that can yield low-resolution structural information, including protein size and shape. Here, we review computational methods that integrate SAXS with other experimental datasets for structural modeling. Finally, we provide a case study of determination of the structure of a protein complex formed between the tandem SH3 domains in c-Cb1-associated protein and the proline-rich loop in human vinculin. Project supported by the National Key Basic Research Program of China (Grant Nos. 2013CB910203 and 2011CB911104), the National Natural Science Foundation of China (Grant No. 31270760), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB08030102), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20113402120013).

  13. Ultrasonic degradation of polysaccharides studied by multi-angle laser light scattering

    NASA Astrophysics Data System (ADS)

    Eschette, Regina; Norwood, David

    2003-03-01

    Ultrasonic degradation of polymers is a well-studied field. It is understood that the degradation process results from shock waves generated by cavitation and collapse. That is, cavities formed when the pressure wave is at a minimum violently collapse as the pressure increases. The rapid collapse sends out shock waves into the material and the main-chain rupture is believed to stem from this rapid motion of solvents. We explore this process using the experimental technique of multi-angle light scattering (MALLS). MALLS provides the molecular weight, RMS radius and virial coefficient of polymers in dilute solution. We monitor the change in these parameters as a function of time exposed to ultrasound for three polymers: Xanthan, Hyaluronic acid (HA), and Lambda Carrageenan (LC). These polysaccharides are chosen because they have similar initial molecular weights ( 10 ^6 g/mol) but different architectures. Xanthan is a wormlike chain, HA is an expanded random coil (large persistence length) and LC is a contracted random coil (small persistence length).

  14. Alzheimer's disease imaging biomarkers using small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Choi, Mina; Alam, Nadia; Dahal, Eshan; Ghammraoui, Bahaa; Badano, Aldo

    2016-03-01

    There is a need for novel imaging techniques for the earlier detection of Alzheimer's disease (AD). Two hallmarks of AD are amyloid beta (Aβ) plaques and tau tangles that are formed in the brain. Well-characterized x-ray cross sections of Aβ and tau proteins in a variety of structural states could potentially be used as AD biomarkers for small-angle x-ray scattering (SAXS) imaging without the need for injectable probes or contrast agents. First, however, the protein structures must be controlled and measured to determine accurate biomarkers for SAXS imaging. Here we report SAXS measurements of Aβ42 and tau352 in a 50% dimethyl sulfoxide (DMSO) solution in which these proteins are believed to remain monomeric because of the stabilizing interaction of DMSO solution. Our SAXS analysis showed the aggregation of both proteins. In particular, we found that the aggregation of Aβ42 slowly progresses with time in comparison to tau352 that aggregates at a faster rate and reaches a steady-state. Furthermore, the measured signals were compared to the theoretical SAXS profiles of Aβ42 monomer, Aβ42 fibril, and tau352 that were computed from their respective protein data bank structures. We have begun the work to systematically control the structural states of these proteins in vitro using various solvent conditions. Our future work is to utilize the distinct SAXS profiles of various structural states of Aβ and tau to build a library of signals of interest for SAXS imaging in brain tissue.

  15. 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.

  16. High-angle light scattering to determine the optical fiber core

    NASA Astrophysics Data System (ADS)

    Świrniak, Grzegorz

    2015-06-01

    The aim of the paper is to discuss the possibility of non-invasive sizing of a step-index optical fiber with the use of a beam of light of low temporal coherence. For this purpose we examine the angular profile of light scattered from the fiber at a high angle. The scattered pattern comprises chiefly two coupled, twin rainbows and depends on the fiber physical characteristics, i.e. its dimensions, shape, and refractive index profile. In order to find a causal link between the scattering pattern and the fiber morphology, a spectral analysis (Fast Fourier Transform, FFT) is performed over the scattering intensity. From the spectral data, the core diameter of a step-index optical fiber is extracted inversely.

  17. A Hierarchical Algorithm for Fast Debye Summation with Applications to Small Angle Scattering

    PubMed Central

    Gumerov, Nail A.; Berlin, Konstantin; Fushman, David; Duraiswami, Ramani

    2012-01-01

    Debye summation, which involves the summation of sinc functions of distances between all pair of atoms in three dimensional space, arises in computations performed in crystallography, small/wide angle X-ray scattering (SAXS/WAXS) and small angle neutron scattering (SANS). Direct evaluation of Debye summation has quadratic complexity, which results in computational bottleneck when determining crystal properties, or running structure refinement protocols that involve SAXS or SANS, even for moderately sized molecules. We present a fast approximation algorithm that efficiently computes the summation to any prescribed accuracy ε in linear time. The algorithm is similar to the fast multipole method (FMM), and is based on a hierarchical spatial decomposition of the molecule coupled with local harmonic expansions and translation of these expansions. An even more efficient implementation is possible when the scattering profile is all that is required, as in small angle scattering reconstruction (SAS) of macromolecules. We examine the relationship of the proposed algorithm to existing approximate methods for profile computations, and show that these methods may result in inaccurate profile computations, unless an error bound derived in this paper is used. Our theoretical and computational results show orders of magnitude improvement in computation complexity over existing methods, while maintaining prescribed accuracy. PMID:22707386

  18. Coherent Detector for Near-Angle Scattering and Polarization Characterization of Telescope Mirror Coatings

    NASA Technical Reports Server (NTRS)

    Macenka, Steven A.; Chipman, Russell A.; Daugherty, Brian J.; McClain, Stephen C.

    2012-01-01

    A report discusses the difficulty of measuring scattering properties of coated mirrors extremely close to the specular reflection peak. A prototype Optical Hetero dyne Near-angle Scatterometer (OHNS) was developed. Light from a long-coherence-length (>150 m) 532-nm laser is split into two arms. Acousto-optic modulators frequency shift the sample and reference beams, establishing a fixed beat frequency between the beams. The sample beam is directed at very high f/# onto a mirror sample, and the point spread function (PSF) formed after the mirror sample is scanned with a pinhole. This light is recombined by a non-polarizing beam splitter and measured through heterodyne detection with a spectrum analyzer. Polarizers control the illuminated and analyzed polarization states, allowing the polarization dependent scatter to be measured. The bidirectional reflective or scattering distribution function is normally measured through use of a scattering goniometer instrument. The instrumental beam width (collection angle span) over which the scatterometer responds is typically many degrees. The OHNS enables measurement at angles as small as the first Airy disk diameter.

  19. Analysis of low-angle x-ray scattering peaks from lyophilized biological samples

    NASA Astrophysics Data System (ADS)

    Desouky, Omar S.; Elshemey, Wael M.; Selim, Nabila S.; Ashour, Ahmed H.

    2001-08-01

    Low-angle x-ray scattering (LAXS) from lyophilized blood and its constituents is characterized by the presence of two peaks in the forward direction of scattering. These peaks are found to be sensitive to the variations in the molecular structure of a given sample. The present work aims to explore the nature of LAXS from a variety of lyophilized biological samples. It also aims to investigate the possibility that a certain biological macromolecule is responsible of the production of LAXS peaks. This is carried out through measurements of LAXS from complex biological samples and their basic constituents. Among the measured samples are haemoglobin (Hb), globin, haem, packed red blood cells, bovine albumin, egg albumin, milk, casein, glutamine, alanine, fat, muscle and DNA. A table containing some characteristic parameters of the LAXS profiles of these samples is also presented. Analysis of measured profiles shows that all lyophilized samples produce at least one relatively broad peak at a scattering angle around 10.35°. The full width at half maximum (FWHM) of this peak varies considerably among the measured samples. Except for milk and casein, one additional peak at a scattering angle around 4.65° is observed only in the LAXS profiles of proteins or protein-rich samples. This fact strongly suggests protein to be the biological macromolecule from which this characteristic peak originates. The same idea is further strengthened through discussion of some previous observations.

  20. Optical and Geometric Properties of Free Silica Nanoparticles Studied by Small-Angle X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Langer, Burkhard; Raschpichler, Christopher; Gruner, Mathias; Antonsson, Egill; Goroncy, Christian; Graf, Christina; Rühl, Eckart

    2016-09-01

    Elastic small-angle X-ray scattering (SAXS) of free silica (SiO2) nanoparticles is reported (d = 100-180 nm). The particles were prepared by a modified Stöber synthesis in narrow size distributions with controlled surface roughness and functionalization. Angle-resolved small-angle X-ray scattering patterns are shown to be sensitive to these changes in particle properties. It is reported that there is an exponential decrease in scattered X-ray intensity towards larger scattering angles as well as distinct oscillations, which is fully explained by Mie theory. Small-angle X-ray scattering of mesoporous nanoparticles with rough surfaces is compared to that of microporous nanoparticles with smooth surfaces, revealing distinct differences that are rationalized by diffuse scattering from nanoparticle pores in addition to the dominating contribution of Mie scattering. Furthermore, results from small-angle X-ray scattering experiments on functionalized silica nanoparticles are presented, where the incorporation of the dye fluorescein isothiocyanate is found to cause changes in the optical properties of the nanoparticles, as compared to non-functionalized samples. Small, but distinct deviations in particle size derived from electron microscopy and from small-angle X-ray scattering are observed. These are rationalized by particle shrinking occurring in electron microscopy as well as slight changes in optical properties of the nanoparticle samples.

  1. 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.

  2. Chaotic scattering of pitch angles in the current sheet of the magnetotail

    NASA Technical Reports Server (NTRS)

    Burkhart, G. R.; Chen, J.

    1992-01-01

    The modified Harris field model is used to investigate the process of pitch angle scattering by a current sheet. The relationship between the incoming asymptotic pitch angle alpha(in) and the outgoing asymptotic pitch angle alpha(out) is studied from first principles by numerically integrating the equation of motion. Evidence that charged particles undergo chaotic scattering by the current sheet is found. For fixed alpha(in), it is shown that alpha(out) exhibits sensitive dependence on the energy parameter in certain energy ranges. For a fixed energy parameter value in the same energy ranges, alpha(out) sensitively depends on alpha(in). For other energy values, alpha(out) does not show sensitive dependence on alpha(in) for most phase angles. A distribution of alpha(in) is mapped from the asymptotic region to the midplane, and it is found that the resulting particle distribution should have beam structures with well-collimated pitch angles near each resonance energy value. Implications for the particle distribution functions in the earth's magnetotail are discussed.

  3. From small angle x-ray scattering to reflectivity: Instrumentation and sample study

    SciTech Connect

    Hua, D.W.; Beaucage, G.; Kent, M.S.

    1996-02-01

    In this study, we described the first results from an x-ray reflectometer which has been modified from an existing Kratky small angle x-ray scattering (SAXS) camera at the UNM/Sandia scattering center. Typically, seven orders of magnitude of reflectivity can be obtained over a range of 0.02 to 0.5 A{sup {minus}1} in {ital q}. This allows the resolution of surface features of 10 to 1000 A. The conversion to reflectometer is reversible and can be achieved in a short time, allowing for dual use of an existing Kratky camera. {copyright} {ital 1996 Materials Research Society.}

  4. Small Angle Neutron Scattering Observation of Chain Retraction after a Large Step Deformation

    SciTech Connect

    Blanchard, A.; Heinrich, M.; Pyckhout-Hintzen, W.; Richter, D.; Graham, R.S.; Likhtman, A.E.; McLeish, T.C.B.; Read, D.J.; Straube, E.; Kohlbrecher, J.

    2005-10-14

    The process of retraction in entangled linear chains after a fast nonlinear stretch was detected from time-resolved but quenched small angle neutron scattering (SANS) experiments on long, well-entangled polyisoprene chains. The statically obtained SANS data cover the relevant time regime for retraction, and they provide a direct, microscopic verification of this nonlinear process as predicted by the tube model. Clear, quantitative agreement is found with recent theories of contour length fluctuations and convective constraint release, using parameters obtained mainly from linear rheology. The theory captures the full range of scattering vectors once the crossover to fluctuations on length scales below the tube diameter is accounted for.

  5. 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.

  6. Inversion of Dynamical Scattering from Large-Angle Rocking-Beam Electron Diffraction Patterns

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Pennington, Robert S.; Koch, Christoph T.

    2016-07-01

    A method for ab initio structure factor retrieval from large-angle rocking-beam electron diffraction data of thin crystals is described and tested with experimental and simulated data. No additional information, such as atomicity or information about chemical composition, has been made use of. Our numerical experiments show that the inversion of dynamical scattering works best, if the beam tilt range is large and the specimen not too thick, because for moderate multiple scattering, the large tilt amplitude effectively removes local minima in this global optimization problem.

  7. Small angle neutron scattering from nanocrystalline Pd and Co compacted at elevated temperatures

    SciTech Connect

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

    1994-05-01

    Nanocrystalline (n-) Cu and Pd, prepared by inert gas condensation and in situ room temperature (RT) and elevated temperature (warm) compactions, have been studied by small angle neutron scattering (SANS). Previous work on RT compacted and subsequently annealed n-Pd seemed to show that all the scattering could be accounted for by a distribution of pores. Analysis of more extensive SANS measurements, together with results of prompt gamma activation analysis, indicates that the SANS can be explained by the presence of pores and hydrogen. Warm compaction reduces the hydrogen impurity level, while increasing the bulk density and decreasing the pore size. This can lead to a dramatic hardness increase in these materials.

  8. Rainbows in energy- and angle-resolved ion scattering from surfaces

    SciTech Connect

    Tenner, A.D.; Gillen, K.T.; Horn, T.C.M.; Los, J.; Kleyn, A.W.

    1984-06-11

    The angular and energy distributions of K/sup +/ ions scattered at normal incidence with an initial energy of 35 eV on a W(110) surface were measured for various crystal orientations. The complex distributions show rainbows, which are due to both to extrema in the deflection functions for the two scattering angles as well as to an extremum in the final energy as a function of the impact parameter. With use of computer simulations with a nonadditive model potential all observed structures can be explained.

  9. X-ray Scattering Techniques for Characterization of Nanosystems in Lifescience

    SciTech Connect

    Saw, C K

    2005-04-11

    The intent of this chapter is to provide the basics of using x-ray diffraction techniques in order to obtain information on the structure and morphology of the nanosystems, and also to point out some of its strengths and weaknesses when compare to other characterization techniques. X-ray scattering examines over a wide range of density domains from a tenth to a thousandth angstrom. Essentially, this covers a whole range of condensed matter, including the structure and morphology of nanosystems, particularly useful for examining nanostructures in lifescience. This range of domain size requires both the wide-angle x-ray scattering (WAXS) and small-angle (SAXS) x-ray scattering techniques. Roughly WAXS covers from 2 nm down, and SAXS covers from .5 nm to 100 nm and possibly 1,000 nm for a finely tuned instrument. Brief theoretical description of both WAXS and SAXS will be given in this chapter. WAXS, by itself is a powerful technique in providing information on the crystallographic structure or lack of structure, atomic positions and sizes in a unit cell, to some extend, chemical compositions and as well as chemical stoichiometry. Examples of such experiments will also be given. In order to be able to describe the technique of x-ray scattering, some historical and theoretical background will be given in the hope of making this subject interesting and simple.

  10. Understanding inelastically scattered neutrons from water on a time-of-flight small-angle neutron scattering (SANS) instrument

    NASA Astrophysics Data System (ADS)

    Do, Changwoo; Heller, William T.; Stanley, Christopher; Gallmeier, Franz X.; Doucet, Mathieu; Smith, Gregory S.

    2014-02-01

    It is generally assumed by most of the small-angle neutron scattering (SANS) user community that a neutron's energy is unchanged during SANS measurements. Here, the scattering from water, specifically light water, was measured on the EQ-SANS instrument, a time-of-flight (TOF) SANS instrument located at the Spallation Neutron Source of Oak Ridge National Laboratory. A significant inelastic process was observed in the TOF spectra of neutrons scattered from water. Analysis of the TOF spectra from the sample showed that the scattered neutrons have energies consistent with room-temperature thermal energies (~20 meV) regardless of the incident neutron's energy. With the aid of Monte Carlo particle transport simulations, we conclude that the thermalization process within the sample results in faster neutrons that arrive at the detector earlier than expected based on the incident neutron energies. This thermalization process impacts the measured SANS intensities in a manner that will ultimately be sample- and temperature-dependent, necessitating careful processing of the raw data into the SANS cross-section.

  11. The atomic scale structure of CXV carbon: wide-angle x-ray scattering and modeling studies.

    PubMed

    Hawelek, L; Brodka, A; Dore, J C; Honkimaki, V; Burian, A

    2013-11-13

    The disordered structure of commercially available CXV activated carbon produced from finely powdered wood-based carbon has been studied using the wide-angle x-ray scattering technique, molecular dynamics and density functional theory simulations. The x-ray scattering data has been converted to the real space representation in the form of the pair correlation function via the Fourier transform. Geometry optimizations using classical molecular dynamics based on the reactive empirical bond order potential and density functional theory at the B3LYP/6-31g* level have been performed to generate nanoscale models of CXV carbon consistent with the experimental data. The final model of the structure comprises four chain-like and buckled graphitic layers containing a small percentage of four-fold coordinated atoms (sp(3) defects) in each layer. The presence of non-hexagonal rings in the atomic arrangement has been also considered. PMID:24140935

  12. The atomic scale structure of CXV carbon: wide-angle x-ray scattering and modeling studies

    NASA Astrophysics Data System (ADS)

    Hawelek, L.; Brodka, A.; Dore, J. C.; Honkimaki, V.; Burian, A.

    2013-11-01

    The disordered structure of commercially available CXV activated carbon produced from finely powdered wood-based carbon has been studied using the wide-angle x-ray scattering technique, molecular dynamics and density functional theory simulations. The x-ray scattering data has been converted to the real space representation in the form of the pair correlation function via the Fourier transform. Geometry optimizations using classical molecular dynamics based on the reactive empirical bond order potential and density functional theory at the B3LYP/6-31g* level have been performed to generate nanoscale models of CXV carbon consistent with the experimental data. The final model of the structure comprises four chain-like and buckled graphitic layers containing a small percentage of four-fold coordinated atoms (sp3 defects) in each layer. The presence of non-hexagonal rings in the atomic arrangement has been also considered.

  13. Shack-Hartmann-based objective straylight assessment of the human eye in an increased scattering angle range

    NASA Astrophysics Data System (ADS)

    Schramm, Stefan; Schikowski, Patrick; Lerm, Elena; Kaeding, André; Haueisen, Jens; Baumgarten, Daniel

    2016-07-01

    Objective measurement of straylight in the human eye with a Shack-Hartmann (SH) wavefront aberrometer is limited in imaging angle. We propose a measurement principle and a point spread function (PSF) reconstruction algorithm to overcome this limitation. In our optical setup, a variable stop replaces the stop conventionally used to suppress reflections and scatter in SH aberrometers. We record images with 21 diameters of the stop. From each SH image, the average intensity of the pupil is computed and normalized. The intensities represent integral values of the PSF. We reconstruct the PSF, which is the derivative of the intensities with respect to the visual angle. A modified Stiles Holladay approximation is fitted to the reconstructed PSF, resulting in a straylight parameter. A proof-of-principle study was carried out on eight healthy young volunteers. Scatter filters were positioned in front of the volunteers' eyes to simulate straylight. The straylight parameter was compared to the C-Quant measurements and the filter values. The PSF parameter shows strong correlation with the density of the filters and a linear relation to the C-Quant straylight parameter. Our measurement and reconstruction techniques allow for objective straylight analysis of visual angles up to 4 deg.

  14. Failure of the multiple peaking approximation for fast capture processes at milliradian scattering angles

    SciTech Connect

    Houamer, Salim; Popov, Yuri V.; Dal Cappello, Claude

    2010-03-15

    The first Born approximation is examined for different fast capture processes for the p+He system at incident energies of about 1 MeV. Calculations have been performed for the singly differential cross section (SDCS) for scattering angles 0-0.5 mrad in the laboratory frame. In the case of transfer ionization, we observe that the two-step-2 mechanism has a dominant contribution to the SDCS for the kinematics considered in this work. The present investigation demonstrates that the multiple peaking approximation is a very crude method which fails to describe the SDCS even at scattering angles below 0.5 mrad. We have also presented a doubly differential cross section for the fixed emission energy of 600 eV and compared our results with other theoretical calculations and experiments.

  15. 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

  16. Angle-resolved surface-enhanced Raman scattering on metallic nanostructured plasmonic crystals.

    PubMed

    Baumberg, Jeremy J; Kelf, Timothy A; Sugawara, Yoshihiro; Cintra, Suzanne; Abdelsalam, Mamdouh E; Bartlett, Phillip N; Russell, Andrea E

    2005-11-01

    Surface-enhanced Raman scattering is an ideal tool for identifying molecules from the "fingerprint" of their molecular bonds; unfortunately, this process lacks a full microscopic understanding and, practically, is plagued with irreproducibility. Using nanostructured metal surfaces, we demonstrate strong correlations between plasmon resonances and Raman enhancements. Evidence for simultaneous ingoing and outgoing resonances in wavelength and angle sheds new light on the Raman enhancement process, allowing optimization of a new generation of reproducible Raman substrates.

  17. 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.

  18. Pore size distribution of shaley rock by small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Hall, P. L.; Mildner, D. F. R.; Borst, R. L.

    1983-08-01

    Information concerning pore microstructure of shaly rocks is of considerable relevance to petroleum exploration and production. Pore sizes and distributions within shaly samples have been determined by small angle neutron scattering. The data are indicative of a considerable spread of pore dimension, showing inhomogeneities with a range from 20 Å and greater. The cumulative pore volumes are compared with those derived from mercury intrusion porosimetry and nitrogen adsorption and desorption isotherms.

  19. Pore size distribution of shaly rock by small angle neutron scattering

    SciTech Connect

    Hall, P.L.; Mildner, D.F.R.; Borst, R.L.

    1983-08-01

    Information concerning pore microstructure of shaly rocks is of considerable relevance to petroleum exploration and production. Pore sizes and distributions within shaly samples have been determined by small angle neutron scattering. The data are indicative of a considerable spread of pore dimension, showing inhomogeneities with a range from 20 A and greater. The cumulative pore volumes are compared with those derived from mercury intrusion porosimetry and nitrogen adsorption and desorption isotherms.

  20. Monte Carlo-based rigid body modelling of large protein complexes against small angle scattering data.

    PubMed

    Meesters, Christian; Pairet, Bruno; Rabenhorst, Anja; Decker, Heinz; Jaenicke, Elmar

    2010-06-01

    We present a modular, collaborative, open-source architecture for rigid body modelling based upon small angle scattering data, named sas_rigid. It is designed to provide a fast and extensible scripting interface using the easy-to-learn Python programming language. Features include rigid body modelling to result in static structures and three-dimensional probability densities using two different algorithms. PMID:20598639

  1. 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).

  2. Angle-resolved second harmonic light scattering from colloidal suspensions and second harmonic particle microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Ningping

    2001-08-01

    We have carried out two nonlinear optical experiments with colloidal particles. Our first nonlinear optical experiment studied Second-Harmonic Generation (SHG) light scattering from colloidal suspension. In particular, we measured the angle-resolved second-harmonic generation light scattering from suspensions of centrosymmetric micron-size polystyrene spheres with surface-adsorbed dye (malachite green). The second-harmonic scattering angular profiles differ qualitatively from the linear light scattering angular profiles of the same particles. We have investigated these radiation patterns using several polarization configurations and particle diameters. We introduce a simple Rayleigh-Gans-Debye model to account for the SHG scattering anisotropy. The model compares favorably with our experimental data. Our measurements suggest scattering anisotropy may be used to isolate particle nonlinear optical effect from other bulk nonlinear optical effects in suspension. Our second nonlinear optical experiment studied the Second-Harmonic Generation (SHG) from single micron-size particles. We built a nonlinear optical microscope for this purpose. We report experimental observations of second harmonic generation from single micron-size polystyrene (PS), silica, and PolyMethylMethAcrylate (PMMA) spheres on flat substrates by SHG microscopy. At low input light intensities the SH signals depend quadratically on the intensity of the excitation beam, but at larger input intensities some of the SH signals increase exponentially with increasing input intensity. This exponential enhancement depends on particle size and sphere composition. We describe the experiments, report the observations and provide an approximate analytical framework for understanding our measurements.

  3. 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.

  4. Method and Apparatus for Measuring Near-Angle Scattering of Mirror Coatings

    NASA Technical Reports Server (NTRS)

    Chipman, Russell A. (Inventor); Daugherty, Brian J. (Inventor); McClain, Stephen C. (Inventor); Macenka, Steven A. (Inventor)

    2013-01-01

    Disclosed herein is a method of determining the near angle scattering of a sample reflective surface comprising the steps of: a) splitting a beam of light having a coherence length of greater than or equal to about 2 meters into a sample beam and a reference beam; b) frequency shifting both the sample beam and the reference beam to produce a fixed beat frequency between the sample beam and the reference beam; c) directing the sample beam through a focusing lens and onto the sample reflective surface, d) reflecting the sample beam from the sample reflective surface through a detection restriction disposed on a movable stage; e) recombining the sample beam with the reference beam to form a recombined beam, followed by f) directing the recombined beam to a detector and performing heterodyne analysis on the recombined beam to measure the near-angle scattering of the sample reflective surface, wherein the position of the detection restriction relative to the sample beam is varied to occlude at least a portion of the sample beam to measure the near-angle scattering of the sample reflective surface. An apparatus according to the above method is also disclosed.

  5. 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.

  6. 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.

  7. Nanopores in track-etched polymer membranes characterized by small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Cornelius, T. W.; Schiedt, B.; Severin, D.; Pépy, G.; Toulemonde, M.; Apel, P. Yu; Boesecke, P.; Trautmann, C.

    2010-04-01

    Nanochannels and nanowires with diameters ranging from 30 to 400 nm were produced by etching ion tracks in thin polyarylate and polycarbonate foils. The shape and the size distribution of dry and wet nanochannels, as well as of nanowires grown therein, were examined by small-angle x-ray scattering. The x-ray intensity as a function of the scattering vector exhibits pronounced oscillations showing that both the channels and the wires have a highly cylindrical geometry and a very narrow size distribution. UV exposure before chemical etching significantly improves the monodispersity of the nanopores. For fixed etching conditions, the scattering patterns provide evidence that the diameter of dry and water-filled channels as well as for embedded nanowires are identical, demonstrating that the pores in the polymer are completely filled.

  8. Small-angle scattering instruments on a 1 MW long pulse spallation source

    SciTech Connect

    Olah, G.A.; Hjelm, R.P.; Seeger, P.A.

    1995-12-01

    Two small-angle neutron scattering instruments have been designed and optimized for installation at a 1 MW long pulse spallation source. The first of these instruments allows access to length scales in materials from 10 to 400 {angstrom}, and the second instrument from 40 to 1200 {angstrom}. Design characteristics were determined and optimization was done using the MCLIB Monte Carlo instrument simulation package. The code has been {open_quote}benchmarked{close_quote} by simulating the {open_quote}as-built{close_quote} D11 spectrometer at ILL and a performance comparison of the three instruments was made. Comparisons were made by evaluating the scattered intensity for {delta} scatterers at different Q values for various instrument configurations needed to span a Q-range of 0.0007 - 0.44 {angstrom}{sup {minus}1}.

  9. MAGNETIC VARIANCES AND PITCH-ANGLE SCATTERING TIMES UPSTREAM OF INTERPLANETARY SHOCKS

    SciTech Connect

    Perri, Silvia; Zimbardo, Gaetano E-mail: gaetano.zimbardo@fis.unical.it

    2012-07-20

    Recent observations of power-law time profiles of energetic particles accelerated at interplanetary shocks have shown the possibility of anomalous, superdiffusive transport for energetic particles throughout the heliosphere. Those findings call for an accurate investigation of the magnetic field fluctuation properties at the resonance frequencies upstream of the shock's fronts. Normalized magnetic field variances, indeed, play a crucial role in the determination of the pitch-angle scattering times and then of the transport regime. The present analysis investigates the time behavior of the normalized variances of the magnetic field fluctuations, measured by the Ulysses spacecraft upstream of corotating interaction region (CIR) shocks, for those events which exhibit superdiffusion for energetic electrons. We find a quasi-constant value for the normalized magnetic field variances from about 10 hr to 100 hr from the shock front. This rules out the presence of a varying diffusion coefficient and confirms the possibility of superdiffusion for energetic electrons. A statistical analysis of the scattering times obtained from the magnetic fluctuations upstream of the CIR events has also been performed; the resulting power-law distributions of scattering times imply long range correlations and weak pitch-angle scattering, and the power-law slopes are in qualitative agreement with superdiffusive processes described by a Levy random walk.

  10. Small-Angle X-ray Scattering Demonstrates Similar Nanostructure in Cortical Bone from Young Adult Animals of Different Species.

    PubMed

    Kaspersen, Jørn Døvling; Turunen, Mikael Juhani; Mathavan, Neashan; Lages, Sebastian; Pedersen, Jan Skov; Olsson, Ulf; Isaksson, Hanna

    2016-07-01

    Despite the vast amount of studies focusing on bone nanostructure that have been performed for several decades, doubts regarding the detailed structure of the constituting hydroxyapatite crystal still exist. Different experimental techniques report somewhat different sizes and locations, possibly due to different requirements for the sample preparation. In this study, small- and wide-angle X-ray scattering is used to investigate the nanostructure of femur samples from young adult ovine, bovine, porcine, and murine cortical bone, including three different orthogonal directions relative to the long axis of the bone. The radially averaged scattering from all samples reveals a remarkable similarity in the entire q range, which indicates that the nanostructure is essentially the same in all species. Small differences in the data from different directions confirm that the crystals are elongated in the [001] direction and that this direction is parallel to the long axis of the bone. A model consisting of thin plates is successfully employed to describe the scattering and extract the plate thicknesses, which are found to be in the range of 20-40 Å for most samples but 40-60 Å for the cow samples. It is demonstrated that the mineral plates have a large degree of polydispersity in plate thickness. Additionally, and equally importantly, the scattering data and the model are critically evaluated in terms of model uncertainties and overall information content.

  11. Small-Angle X-ray Scattering Demonstrates Similar Nanostructure in Cortical Bone from Young Adult Animals of Different Species.

    PubMed

    Kaspersen, Jørn Døvling; Turunen, Mikael Juhani; Mathavan, Neashan; Lages, Sebastian; Pedersen, Jan Skov; Olsson, Ulf; Isaksson, Hanna

    2016-07-01

    Despite the vast amount of studies focusing on bone nanostructure that have been performed for several decades, doubts regarding the detailed structure of the constituting hydroxyapatite crystal still exist. Different experimental techniques report somewhat different sizes and locations, possibly due to different requirements for the sample preparation. In this study, small- and wide-angle X-ray scattering is used to investigate the nanostructure of femur samples from young adult ovine, bovine, porcine, and murine cortical bone, including three different orthogonal directions relative to the long axis of the bone. The radially averaged scattering from all samples reveals a remarkable similarity in the entire q range, which indicates that the nanostructure is essentially the same in all species. Small differences in the data from different directions confirm that the crystals are elongated in the [001] direction and that this direction is parallel to the long axis of the bone. A model consisting of thin plates is successfully employed to describe the scattering and extract the plate thicknesses, which are found to be in the range of 20-40 Å for most samples but 40-60 Å for the cow samples. It is demonstrated that the mineral plates have a large degree of polydispersity in plate thickness. Additionally, and equally importantly, the scattering data and the model are critically evaluated in terms of model uncertainties and overall information content. PMID:26914607

  12. Measurement technique for bottom scattering in shallow water

    PubMed

    Holland; Hollett; Troiano

    2000-09-01

    Sonar performance predictions of reverberation in shallow water rely upon good estimates of the bottom-scattering strength. However, little is understood about bottom scattering in shallow water in the frequency range 400-4000 Hz, particularly its dependency upon frequency and its relationship to the physical properties of the seafloor. In order to address these issues, a new measurement technique has been developed to probe the frequency and angular dependency of bottom-scattering strength. The experimental technique is described which employs either coherent or incoherent sources (lightbulbs). In addition, measurement and modeling results for two diverse shallow water sites are presented. At one site, the scattering appears to arise at or near the water-sediment interface. At the other site, scattering from a 23-m sub-bottom horizon is clearly apparent in the data at and below 1800 Hz. The fact that our measurement technique can directly reveal the presence of sub-bottom scattering is a significant advance in the development of methods to explore the physical mechanisms that control bottom scattering.

  13. EDITORIAL Proceedings of the XIV International Conference on Small-Angle Scattering, SAS-2009

    NASA Astrophysics Data System (ADS)

    Ungar, Goran; Heenan, Richard

    2010-10-01

    There are 52 papers in these Proceedings. The papers are divided into 10 thematic sections and a section for invited papers and reviews. The sections and the respective section editors are given below. Section Editor(s) Invited Papers and Reviews Peter Griffiths, Wim Bras, Rudolf Winter Beamlines and Instrumentation Elliot Gilbert, Wim Bras, Nigel Rhodes Theory, Data processing and Modelling Jan Skov Pedersen, Carlo Knupp Biological Systems and Membranes Richard Heenan, Cameron Neylon Ceramics, Glasses and Porous Materials Rudolf Winter Colloids and Solutions Peter Griffiths Hierarchical Structures and Fibres Steve Eichhorn, Karen Edler Metallic and Magnetic Systems Armin Hoell Polymers Patrick Fairclough Time resolved Diffraction, Kinetic and Dynamical Studies João Cabral, Christoph Rau We are grateful to all section editors and the many anonymous referees for their invaluable effort which made the publication of the Proceedings possible. The refereeing process was strict and thorough, some papers were rejected and most were improved. The resulting compendium gives a good overview of recent developments in small-angle X-ray and neutron scattering theory, application, methods of analysis and instrumentation. Thus it should be a useful source of reference for a number of years to come. The papers are a good reflection of the material presented at the meeting. Because of the general high quality of the articles, it was difficult to decide which to highlight and be fair to all contributors. The following in particular have caught the attention of the editors. Highlighted papers A statistical survey of publications reporting the application of SAXS and SANS by Aldo Craievich (paper 012003) is recommended reading for anyone needing convincing about the vibrancy of this scientific field and the ever expanding use of these techniques. Two aspects of coherent X-ray scattering, made available by the advent of the 3rd generation synchrotron sources, are discussed in the

  14. Facilitating model reconstruction for single-particle scattering using small-angle X-ray scattering methods1

    PubMed Central

    Ma, Shufen; Liu, Haiguang

    2016-01-01

    X-ray free-electron lasers generate intense femtosecond X-ray pulses, so that high-resolution structure determination becomes feasible from noncrystalline samples, such as single particles or single molecules. At the moment, the orientation of sample particles cannot be precisely controlled, and consequently the unknown orientation needs to be recovered using computational algorithms. This delays the model reconstruction until all the scattering patterns have been re-oriented, which often entails a long elapse of time and until the completion of the experiment. The scattering patterns from single particles or multiple particles can be summed to form a virtual powder diffraction pattern, and the low-resolution region, corresponding to the small-angle X-ray scattering (SAXS) regime, can be analysed using existing SAXS methods. This work presents a pipeline that converts single-particle data sets into SAXS data, from which real-time model reconstruction is achieved using the model retrieval approach implemented in the software package SASTBX [Liu, Hexemer & Zwart (2012). J. Appl. Cryst.45, 587–593]. To illustrate the applications, two case studies are presented with real experimental data sets collected at the Linac Coherent Light Source. PMID:27047310

  15. Generalized ISAR--part II: interferometric techniques for three-dimensional location of scatterers.

    PubMed

    Given, James A; Schmidt, William R

    2005-11-01

    This paper is the second part of a study dedicated to optimizing diagnostic inverse synthetic aperture radar (ISAR) studies of large naval vessels. The method developed here provides accurate determination of the position of important radio-frequency scatterers by combining accurate knowledge of ship position and orientation with specialized signal processing. The method allows for the simultaneous presence of substantial Doppler returns from both change of roll angle and change of aspect angle by introducing generalized ISAR ates. The first paper provides two modes of interpreting ISAR plots, one valid when roll Doppler is dominant, the other valid when the aspect angle Doppler is dominant. Here, we provide, for each type of ISAR plot technique, a corresponding interferometric ISAR (InSAR) technique. The former, aspect-angle dominated InSAR, is a generalization of standard InSAR; the latter, roll-angle dominated InSAR, seems to be new to this work. Both methods are shown to be efficient at identifying localized scatterers under simulation conditions. PMID:16279180

  16. Generalized ISAR--part II: interferometric techniques for three-dimensional location of scatterers.

    PubMed

    Given, James A; Schmidt, William R

    2005-11-01

    This paper is the second part of a study dedicated to optimizing diagnostic inverse synthetic aperture radar (ISAR) studies of large naval vessels. The method developed here provides accurate determination of the position of important radio-frequency scatterers by combining accurate knowledge of ship position and orientation with specialized signal processing. The method allows for the simultaneous presence of substantial Doppler returns from both change of roll angle and change of aspect angle by introducing generalized ISAR ates. The first paper provides two modes of interpreting ISAR plots, one valid when roll Doppler is dominant, the other valid when the aspect angle Doppler is dominant. Here, we provide, for each type of ISAR plot technique, a corresponding interferometric ISAR (InSAR) technique. The former, aspect-angle dominated InSAR, is a generalization of standard InSAR; the latter, roll-angle dominated InSAR, seems to be new to this work. Both methods are shown to be efficient at identifying localized scatterers under simulation conditions.

  17. Seismic scattering of low-grazing-angle acoustic waves incident on the seafloor

    NASA Astrophysics Data System (ADS)

    Greaves, Robert John

    The goal of this thesis is to develop a methodology to interpret sound scattered from the seafloor in terms of seafloor structure and subseafloor geological properties. Specifically, this work has been directed towards the interpretation of matched-filtered, beamformed monostatic acoustic reverberation data acquired on the west flank of the Mid-Atlantic Ridge when the seafloor is insonified by a band-limited, low-grazing-angle acoustic pulse. This research is based on the hypothesis that observed backscatter signals are produced by a combination of seafloor (interface) scattering and subseafloor (volume) scattering from structure having variations at scale lengths similar to the wavelength of the insonifying acoustic field. Analysis of monostatic reverberation data acquired during the Site A experiment (Run 1) of the Acoustic Reverberation Special Research Program 1993 Acoustics Cruise suggests that the scattered signals cannot be accounted for quantitatively in terms of large- scale slope, even though a strong correspondence between high intensity backscatter and seafloor ridges is observed. In order to investigate and quantify the actual sources of seafloor scattering, a numerical modeling study of seafloor models is undertaken using a finite- difference solution to the elastic wave equation. Geological data available at Site A and published reports describing geological properties of similar deep ocean crustal regions are used to develop a realistic seafloor model for the study area with realistic constraints on elastic parameters. Wavelength-scale heterogeneity in each model, in the form of seafloor roughness and subseafloor volume heterogeneity is defined using stochastic distributions with Gaussian autocorrelations. These distributions are quantified by their correlation lengths and standard deviation in amplitude. In order to incorporate all seafloor structure in a single parameterization of seafloor scattering, large-scale slope and wavelength

  18. 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

  19. Synchrotron Small-Angle X-ray Scattering Study of Cross-Linked Polymeric Micelles.

    PubMed

    Kim, Hyun-Chul; Jin, Kyeong Sik; Lee, Se Guen; Kim, Eunjoo; Lee, Sung Jun; Jeong, Sang Won; Lee, Seung Woo; Kim, Kwang-Woo

    2016-06-01

    Polymeric micelles of methoxypoly(ethylene glycol)-b-poly(lactide) containing lysine units (mPEG-PLA-Lys4) were cross-linked by reacting of lysine moieties with a bifunctional bis(N-hydroxy-succinimide ester). The micelles were characterized in aqueous solution using dynamic light scattering, transmission electron microscopy, and synchrotron small-angle X-ray scattering. The mPEG-PLA-Lys4 was synthesized through the ring-opening polymerization of N6-carbobenzyloxy-L-lysine N-carboxyanhydride with amine-terminated mPEG-PLA and subsequent deprotection. The polymeric micelles showed enhanced micelle stability after cross-linking, which was confirmed by adding sodium dodecyl sulfate as a destabilizing agent. The average diameters measured via dynamic light scattering were 19.1 nm and 29.2 nm for non-cross-linked polymeric micelles (NCPMs) and cross-linked polymeric micelles (CPMs), respectively. The transmission electron microscopy images showed that the size of the polymeric micelles increased slightly due to cross-linking, which was in good agreement with the DLS measurements. The overall structures and internal structural changes of NCPMs and CPMs in aqueous solution were studied in detail using synchrotron X-ray scattering method. According to the structural parameters of X-ray scattering analysis, CPMs with a more densely packed core structure were formed by reacting bifunctional cross-linking agents with lysine amino groups located in the innermost core of the polymeric micelles. PMID:27427731

  20. 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.

  1. Electron-nucleus scattering at small angles in the field of a pulsed laser wave

    NASA Astrophysics Data System (ADS)

    Lebed', A. A.

    2016-04-01

    We study scattering of an electron by a screened potential of a nucleus in the field of a pulsed laser wave at small scattering angles. The interaction of an electron with the field of a nucleus is considered in the first Born approximation. An external field of a pulsed laser is accounted accurately as a quasimonochromatic wave. Analytical expressions are obtained for the transition amplitude and the cross section of the considered process. Scattering kinematics is defined at the minimal value of a transferred momentum. In this case the cross section contains a peak near the preferred scattering direction. It is shown that the maximum value of the cross section is determined by both the initial-electron energy and the energy of an external-field photon. Thus, the cross section of electron-nucleus scattering in a pulsed laser field can exceed in two orders of magnitude the cross section in absence of an external field in the case of ultrarelativistic energies and external field of a free-electron laser with keV-order photon energy.

  2. Bistatic, above-critical angle scattering measurements of fully buried unexploded ordnance (UXO) and clutter.

    PubMed

    Waters, Z J; Simpson, H J; Sarkissian, A; Dey, S; Houston, B H; Bucaro, J A; Yoder, T J

    2012-11-01

    Laboratory grade bistatic scattering measurements are conducted in order to examine the acoustic response of realistic fully buried unexploded ordnance (UXO) from above-critical angle insonification, between 2 and 40 kHz. A 127 mm diameter rocket UXO, a 155 mm diameter artillery shell, a natural rock of approximately the same size, and a cinder block are fully buried in water-saturated medium grained sand (mean grain diameter, 240 μm) at depths of 10 cm below the water-sediment interface. A two-dimensional array of bistatic scattering measurements is generated synthetically by scanning a single hydrophone in steps of 3 cm over a 1 m × 1 m patch directly above the targets at a height of 20 cm above the water-sediment interface. Three-dimensional volumetric acoustic images generated from the return waveforms reveal scattering components attributed to geometric and elastic scattering, as well as multiple-scattering interactions of returns between the sediment-water interface and the buried objects. The far-field target strength of the objects is estimated through extrapolation of the angular spectrum. Agreement is found between experimental data and simulated data generated from a finite-element-based, three-dimensional time-harmonic model (2-25 kHz). Separation of the measured UXO from the clutter objects is demonstrated through exploitation of structural-acoustics-based features.

  3. Bistatic, above-critical angle scattering measurements of fully buried unexploded ordnance (UXO) and clutter.

    PubMed

    Waters, Z J; Simpson, H J; Sarkissian, A; Dey, S; Houston, B H; Bucaro, J A; Yoder, T J

    2012-11-01

    Laboratory grade bistatic scattering measurements are conducted in order to examine the acoustic response of realistic fully buried unexploded ordnance (UXO) from above-critical angle insonification, between 2 and 40 kHz. A 127 mm diameter rocket UXO, a 155 mm diameter artillery shell, a natural rock of approximately the same size, and a cinder block are fully buried in water-saturated medium grained sand (mean grain diameter, 240 μm) at depths of 10 cm below the water-sediment interface. A two-dimensional array of bistatic scattering measurements is generated synthetically by scanning a single hydrophone in steps of 3 cm over a 1 m × 1 m patch directly above the targets at a height of 20 cm above the water-sediment interface. Three-dimensional volumetric acoustic images generated from the return waveforms reveal scattering components attributed to geometric and elastic scattering, as well as multiple-scattering interactions of returns between the sediment-water interface and the buried objects. The far-field target strength of the objects is estimated through extrapolation of the angular spectrum. Agreement is found between experimental data and simulated data generated from a finite-element-based, three-dimensional time-harmonic model (2-25 kHz). Separation of the measured UXO from the clutter objects is demonstrated through exploitation of structural-acoustics-based features. PMID:23145593

  4. Research on ship wake detection by optical method of small angle forward scattering

    NASA Astrophysics Data System (ADS)

    Zhu, Donghua; Rao, Jionghui; Zhang, Xiaohui; Sun, ChunSheng

    2008-03-01

    A ship wake in the ocean contains lots of microsize air bubbles with diameter of 10μm~200μm. When a beam of light propagates through the ship wake, it leads to attenuation of the light energy and change of its spatial distribution due to absorption and scattering caused by ocean water and bubble mass together, but they don't share the same scattering mechanism, leaving absorption out of account. Scattering from micro bubbles can usually be explained by Mie scattering theory. In this paper, a method based on optical scattering theory is proposed for detecting the target of ship wake in the ocean, and an experimental system is built up according to the Lambert-Beer law. In the experiment, a semiconductor laser with wavelength about 532nm was employed as the light source, an experimental device which modeled the target of a ship wake to generate bubble mass in water, and a high-speed PIN photodiode as the detector. Besides, the optical receiving system included a set of optical lens and apertures, which were employed to limit the field of view(FOV) of the receiver detector. After measurement of the small angle forward scattering rays scattered from bubble mass with a small FOV, the target signals was got and processed. Then adjustments were made to the optical receiving system and experiments were implemented with varying the FOV to find out the influence of FOV on target signal SNR and obtain the optimum FOV. The results showed that adjusting the FOV according to different microbubble size density could improve SNR.

  5. Two-scale treatment of low-grazing-angle scattering from spilling breaker water waves

    NASA Astrophysics Data System (ADS)

    West, James C.; Ja, Shiou-Jyh

    2002-07-01

    A two-scale scattering analysis is applied to two series of profiles that represent the measured time evolution of the crests of spilling breaker waves that were mechanically generated and measured in a wave tank. The backscattering at microwave frequencies and low-grazing-angle (LGA) illumination were considered. A deterministic implementation of the perturbation theory that is the foundation of any two-scale scattering model (TSM) is used that allows an instantaneous comparison of TSM cross sections with reference ``exact'' cross sections found using a numerical moment-method-based electromagnetic approach. TSM proved unable to model the scattering from steep features that appear on the crest both before and after the onset of breaking, even in cases where the horizontal-to-vertical polarization ratios are as low as -10 dB. This shows that the ``fast'' scattering (with Doppler speeds greater than or equal to the velocity of the breaker) associated with these features is not due to Bragg scattering in the traditional sense in these cases despite the low polarization ratios. TSM is more accurate after the steep features subside and the turbulent ``scar'' roughness is primarily on the front face of the breaker. However, accuracy is lost as the wave propagates and the scar roughness moves to the crest top and back face of the wave. It appears that a scattering coefficient based on the spectral content of the roughness at the Bragg-resonant condition can provide only a rough estimate of the actual LGA scattering coefficient even after the major steep features have disappeared.

  6. 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.

  7. 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

  8. Wide angle Compton scattering on the proton: study of power suppressed corrections

    NASA Astrophysics Data System (ADS)

    Kivel, N.; Vanderhaeghen, M.

    2015-10-01

    We study the wide angle Compton scattering process on a proton within the soft-collinear factorization (SCET) framework. The main purpose of this work is to estimate the effect due to certain power suppressed corrections. We consider all possible kinematical power corrections and also include the subleading amplitudes describing the scattering with nucleon helicity flip. Under certain assumptions we present a leading-order factorization formula for these amplitudes which includes the hard- and soft-spectator contributions. We apply the formalism and perform a phenomenological analysis of the cross section and asymmetries in the wide angle Compton scattering on a proton. We assume that in the relevant kinematical region where -t,-u>2.5 GeV2 the dominant contribution is provided by the soft-spectator mechanism. The hard coefficient functions of the corresponding SCET operators are taken in the leading-order approximation. The analysis of existing cross section data shows that the contribution of the helicity-flip amplitudes to this observable is quite small and comparable with other expected theoretical uncertainties. We also show predictions for double polarization observables for which experimental information exists.

  9. 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.

  10. Optical characterization of liposomes by right angle light scattering and turbidity measurement.

    PubMed

    Matsuzaki, K; Murase, O; Sugishita, K; Yoneyama, S; Akada, K; Ueha, M; Nakamura, A; Kobayashi, S

    2000-07-31

    Liposomes have frequently been used as models of biomembranes or vehicles for drug delivery. However, the systematic characterization of lipid vesicles by right angle light scattering and turbidity has not been carried out despite the usefulness of such studies for size estimation. In this study, liposomes of various sizes were prepared by sonication and extrusion. The mean cumulant radii of the vesicles were determined by dynamic light scattering. The lamellarities were estimated based on fluorescence quenching of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)dipalmitoyl-L-alpha-phosph ati dylethanolamine by sodium dithionite. Right angle light scattering intensity and optical density at 436 nm per unit lipid concentration were measured as a function of vesicle radius. With a vesicle radius < or =100 nm, the optical parameters could be well explained by the Rayleigh-Gans-Debye theory in which the liposomes were modeled as homogeneous spheres with mean refractive indices determined by the volume fractions of lipids in vesicles.

  11. Mirroring within the Fokker-Planck formulation of cosmic ray pitch angle scattering in homogeneous magnetic turbulence

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Klimas, A. J.; Sandri, G.

    1974-01-01

    The Fokker-Planck coefficient for pitch angle scattering, appropriate for cosmic rays in homogeneous, stationary, magnetic turbulence, is computed from first principles. No assumptions are made concerning any special statistical symmetries the random field may have. This result can be used to compute the parallel diffusion coefficient for high energy cosmic rays moving in strong turbulence, or low energy cosmic rays moving in weak turbulence. Becuase of the generality of the magnetic turbulence which is allowed in this calculation, special interplanetary magnetic field features such as discontinuities, or particular wave modes, can be included rigorously. The reduction of this results to previously available expressions for the pitch angle scattering coefficient in random field models with special symmetries is discussed. The general existance of a Dirac delta function in the pitch angle scattering coefficient is demonstrated. It is proved that this delta function is the Fokker-Planck prediction for pitch angle scattering due to mirroring in the magnetic field.

  12. Effects of the Scatter in Sunspot Group Tilt Angles on the Large-scale Magnetic Field at the Solar Surface

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Cameron, R. H.; Schüssler, M.

    2014-08-01

    The tilt angles of sunspot groups represent the poloidal field source in Babcock-Leighton-type models of the solar dynamo and are crucial for the build-up and reversals of the polar fields in surface flux transport (SFT) simulations. The evolution of the polar field is a consequence of Hale's polarity rules, together with the tilt angle distribution which has a systematic component (Joy's law) and a random component (tilt-angle scatter). We determine the scatter using the observed tilt angle data and study the effects of this scatter on the evolution of the solar surface field using SFT simulations with flux input based upon the recorded sunspot groups. The tilt angle scatter is described in our simulations by a random component according to the observed distributions for different ranges of sunspot group size (total umbral area). By performing simulations with a number of different realizations of the scatter we study the effect of the tilt angle scatter on the global magnetic field, especially on the evolution of the axial dipole moment. The average axial dipole moment at the end of cycle 17 (a medium-amplitude cycle) from our simulations was 2.73 G. The tilt angle scatter leads to an uncertainty of 0.78 G (standard deviation). We also considered cycle 14 (a weak cycle) and cycle 19 (a strong cycle) and show that the standard deviation of the axial dipole moment is similar for all three cycles. The uncertainty mainly results from the big sunspot groups which emerge near the equator. In the framework of Babcock-Leighton dynamo models, the tilt angle scatter therefore constitutes a significant random factor in the cycle-to-cycle amplitude variability, which strongly limits the predictability of solar activity.

  13. Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface

    SciTech Connect

    Jiang, J.; Cameron, R. H.; Schüssler, M.

    2014-08-10

    The tilt angles of sunspot groups represent the poloidal field source in Babcock-Leighton-type models of the solar dynamo and are crucial for the build-up and reversals of the polar fields in surface flux transport (SFT) simulations. The evolution of the polar field is a consequence of Hale's polarity rules, together with the tilt angle distribution which has a systematic component (Joy's law) and a random component (tilt-angle scatter). We determine the scatter using the observed tilt angle data and study the effects of this scatter on the evolution of the solar surface field using SFT simulations with flux input based upon the recorded sunspot groups. The tilt angle scatter is described in our simulations by a random component according to the observed distributions for different ranges of sunspot group size (total umbral area). By performing simulations with a number of different realizations of the scatter we study the effect of the tilt angle scatter on the global magnetic field, especially on the evolution of the axial dipole moment. The average axial dipole moment at the end of cycle 17 (a medium-amplitude cycle) from our simulations was 2.73 G. The tilt angle scatter leads to an uncertainty of 0.78 G (standard deviation). We also considered cycle 14 (a weak cycle) and cycle 19 (a strong cycle) and show that the standard deviation of the axial dipole moment is similar for all three cycles. The uncertainty mainly results from the big sunspot groups which emerge near the equator. In the framework of Babcock-Leighton dynamo models, the tilt angle scatter therefore constitutes a significant random factor in the cycle-to-cycle amplitude variability, which strongly limits the predictability of solar activity.

  14. Structure-property relationships in Waspaloy via small angle scattering and electrical resistivity measurements

    SciTech Connect

    Whelchel, R.; Gerhardt, Dr. Rosario; Littrell, Ken

    2010-01-01

    The mechanical properties in superalloys are controlled by the distribution of the {gamma}{prime} precipitate phase. Electrical measurements have been shown to be sensitive to certain aspects of the precipitation process and show promise for predicting the evolving microstructural state in superalloys. Aging experiments were conducted on Waspaloy samples for temperatures between 600 and 950 C for times ranging from 2min to 500h. Particle size distributions were obtained by modeling of small angle scattering (SAS) data, whereas, small precipitate size information, strain, and lattice mismatch data were obtained from X-ray diffraction. The microstructural information was then used to create a figure of merit of electron scattering intended to correlate electrical properties to the precipitate microstructure. The proposed figure of merit shows an empirical correlation with the electrical resistivity data, demonstrating the sensitivity of the resistivity measurements to the precipitation process and coarsening behavior.

  15. Time resolved small angle x-ray scattering reactivity studies on coals, asphaltenes, and polymers.

    SciTech Connect

    Seifert, S.; Thiyagarajan, P.; Winans, R. E.

    1999-07-02

    The objective of this study is to examine changes in the structures of coals, asphaltenes, and polymers in situ with small angle X-ray scattering (SAXS) during thermal treatments. We have built a SAXS instrument at the Basic Energy Sciences Synchrotrons Radiation Center at the Advanced Photon Source that allows us to obtain scattering data on very small samples and in the millisecond time domain. The Argonne Premium Coal samples, petroleum derived asphaltenes, and polymers with functionality to model fossil fuels were used in this study. The information that can be derived from these experiments includes: changes in fractal dimensionality, surface topology, and size and type of porosity. The information is correlated with other methods on the same samples.

  16. 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.

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

    PubMed

    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

    2016-08-28

    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. PMID:27586949

  18. A microstructural comparison of two nuclear-grade martensitic steels using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Fiori, F.; Little, E. A.; Magnani, M.

    1997-06-01

    Results are presented of a small-angle neutron scattering (SANS) study on two 10-13% Cr martensitic stainless steels of interest for nuclear applications, viz. DIN 1.4914 (MANET specification, for fusion reactors) and AISI 410. The investigation has focussed principally on microstructural effects associated with the differences in chromium content between the two alloys. The size distribution functions determined from nuclear and magnetic SANS components for the two steels given identical heat treatments are in accord with an interpretation based on the presence of ˜ 1 nm size CCr aggregates in the microstructure. Much larger (˜ 10 nm) scattering inhomogeneities with different magnetic contrast are also present and tentatively identified as carbides.

  19. 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.

  20. Tackiness of pressure-sensitive adhesives: An ultra-small-angle X-ray scattering investigation

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, P.; Ittner, T.; Petry, W.

    2004-05-01

    The debonding of a model pressure-sensitive adhesive (PSA) poly-n-buthylacrylate is investigated by a combination of the mechanical tack test, optical microscopy and in situ ultra-small-angle X-ray scattering. From the mechanical test, macroscopic values such as force-distance curves are determined. The force-distance curve exhibits the typical non-linear behavior. With microscopy the macroscopic cavitation structure is observed. Scattering addresses the structure of the PSA on a microscopic level for the first time. As a new feature, a sub-structure of the usual optically resolvable macroscopic fibrils between the PSA surface and the probe punch is detected. The sub-structure exists over a large distance between the PSA and the probe surface and remains constant in diameter. This behavior of the sub-structure as well as the dependence of the force plateau on the film thickness are compared with theoretical predictions.

  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. Probing coal reactivity by time-resolved small angle x-ray scattering.

    SciTech Connect

    Winans, R. E.

    1999-01-22

    The objective of this study is to observe changes in coal structure in situ with small angle X-ray scattering (SAXS) during solvent swelling and during pyrolysis. We have built a SAXS instrument at the Basic Energy Sciences Synchrotrons Research Center at the Advanced Photon Source that allows us to obtain scattering patterns in the millisecond time domain. The eight Argonne Premium Coal samples were used in this study. The information that can be derived from these experiments, such as changes in fractal dimensionality and in size and type of porosity, was found to be very rank-dependent. In the swelling experiments, it was noted that for certain coals, structural changes occurred in just a few minutes.

  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. Structural Studies of Bleached Melanin by Synchrotron Small-angle X-ray Scattering

    SciTech Connect

    Littrell, Kenneth C.; Gallas, James M.; Zajac, Gerry W.; Thiyagarajan, Pappannan

    2003-01-01

    Small-angle X-ray scattering was used to measure the effects of chemical bleaching on the size and morphology of tyrosine-derived synthetic melanin dispersed in aqueous media. The average size as measured by the radius of gyration of the melanin particles in solution, at neutral to mildly basic pH, decreases from 16.5 to 12.5 angstroms with increased bleaching. The melanin particles exhibit scattering characteristic of sheet-like structures with a thickness of approximately 11 angstroms at all but the highest levels of bleaching. The scattering data are well described by the form factor for scattering from a pancake-like circular cylinder. These data are consistent with the hypothesis that unbleached melanin, at neutral to mildly basic pH, is a planar aggregate of 6- to 10-nm-sized melanin protomolecules, hydrogen bonded through their quinone and phenolic perimeters. The observed decrease in melanin particle size with increased bleaching is interpreted as evidence for deaggregation, most probably the result of oxidative disruption of hydrogen bonds and an increase in the number of charged, carboxylic acid groups, whereby the melanin aggregates disassociate into units composed of decreasing numbers of protomolecules.

  5. Deterministic fractals: extracting additional information from small-angle scattering data.

    PubMed

    Cherny, A Yu; Anitas, E M; Osipov, V A; Kuklin, A I

    2011-09-01

    The small-angle scattering curves of deterministic mass fractals are studied and analyzed in momentum space. In the fractal region, the curve I(q)q(D) is found to be log-periodic with good accuracy, and the period is equal to the scaling factor of the fractal. Here, D and I(q) are the fractal dimension and the scattering intensity, respectively. The number of periods of this curve coincides with the number of fractal iterations. We show that the log-periodicity of I(q)q(D) in the momentum space is related to the log-periodicity of the quantity g(r)r(3-D) in the real space, where g(r) is the pair distribution function. The minima and maxima positions of the scattering intensity are estimated explicitly by relating them to the pair distance distribution in real space. It is shown that the minima and maxima are damped with increasing polydispersity of the fractal sets; however, they remain quite pronounced even at sufficiently large values of polydispersity. A generalized self-similar Vicsek fractal with controllable fractal dimension is introduced, and its scattering properties are studied to illustrate the above findings. In contrast with the usual methods, the present analysis allows us to obtain not only the fractal dimension and the edges of the fractal region, but also the fractal iteration number, the scaling factor, and the number of structural units from which the fractal is composed.

  6. Precision Measurement of the Weak Mixing Angle in Møller Scattering

    NASA Astrophysics Data System (ADS)

    Anthony, P. L.; Arnold, R. G.; Arroyo, C.; Bega, K.; Biesiada, J.; Bosted, P. E.; Bower, G.; Cahoon, J.; Carr, R.; Cates, G. D.; Chen, J.-P.; Chudakov, E.; Cooke, M.; Decowski, P.; Deur, A.; Emam, W.; Erickson, R.; Fieguth, T.; Field, C.; Gao, J.; Gary, M.; Gustafsson, K.; Hicks, R. S.; Holmes, R.; Hughes, E. W.; Humensky, T. B.; Jones, G. M.; Kaufman, L. J.; Keller, L.; Kolomensky, Yu. G.; Kumar, K. S.; Laviolette, P.; Lhuillier, D.; Lombard-Nelsen, R. M.; Marshall, Z.; Mastromarino, P.; McKeown, R. D.; Michaels, R.; Niedziela, J.; Olson, M.; Paschke, K. D.; Peterson, G. A.; Pitthan, R.; Relyea, D.; Rock, S. E.; Saxton, O.; Singh, J.; Souder, P. A.; Szalata, Z. M.; Turner, J.; Tweedie, B.; Vacheret, A.; Walz, D.; Weber, T.; Weisend, J.; Woods, M.; Younus, I.

    2005-08-01

    We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: APV=[-131±14(stat)±10(syst)]×10-9, leading to the determination of the weak mixing angle sin⁡2θWeff=0.2397±0.0010(stat)±0.0008(syst), evaluated at Q2=0.026GeV2. Combining this result with the measurements of sin⁡2θWeff at the Z0 pole, the running of the weak mixing angle is observed with over 6σ significance. The measurement sets constraints on new physics effects at the TeV scale.

  7. 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.

  8. [Evaluation of molecular weights of hyaluronate preparations by multi-angle laser light scattering].

    PubMed

    Yomota, Chikako

    2003-01-01

    Hyaluronate (HA), a glycosaminoglycan polysaccharide, has been used for osteoarthritis, periartritis of the shoulder and rheumatoid arthritis by intraarticular administration, and in ophthalmic surgery such as anterior segment surgery, and eye lotion. In this study, the molecular weight (Mw) of HA preparations were estimated by size-exclusion chromatography (SEC) system consisted of a refractometer (RI) and a multi-angle laser light scattering (MALS). From the results, it has been clarified that a successful characterization of HA samples with Mw up to 2 - 3 x 10(6) g/mol was possible by multidetector system.

  9. Analysis of C-S-H gel and cement paste by small-angle neutron scattering

    SciTech Connect

    Allen, Andrew J. . E-mail: andrew.allen@nist.gov; Thomas, Jeffrey J. . E-mail: jthomas@northwestern.edu

    2007-03-15

    The role of small-angle X-ray and neutron scattering (SAXS and SANS) in the characterization of cement is briefly reviewed. The unique information obtainable from SANS analysis of C-S-H gel in hydrating cement is compared with that obtainable by other neutron methods. Implications for the nature of C-S-H gel, as detected by SANS, are considered in relation to current models. Finally, the application of the SANS method to cement paste is demonstrated by analyzing the effects of calcium chloride acceleration and sucrose retardation on the resulting hydrated microstructure.

  10. Direct Observation Of Nanoparticle-Surfactant Interactions Using Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Kumar, Sugam; Aswal, V. K.

    2010-12-01

    Interactions of anionic silica nanoparticles with anionic, cationic and nonionic surfactants have directly been studied by contrast variation small angle neutron scattering (SANS). The measurements are performed on 1 wt% of both silica nanoparticles and surfactants of anionic sodium dodecyle sulphate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB) and non-ionic polyoxyethylene 10 lauryl ether (C12E10) in aqueous solution. We show that there is no direct interaction in the case of SDS with silica particles, whereas strong interaction for DTAB leads to the aggregation of silica particles. The interaction of C12E10 is found through the micelles adsorbed on the silica particles.

  11. Small angle scattering polarization biopsy: a comparative analysis of various skin diseases

    NASA Astrophysics Data System (ADS)

    Zimnyakov, D. A.; Alonova, M. V.; Yermolenko, S. B.; Ivashko, P. V.; Reshetnikova, E. M.; Galkina, E. M.; Utz, S. R.

    2013-12-01

    An approach to differentiation of the morphological features of normal and pathological human epidermis on the base of statistical analysis of the local polarization states of laser light forward scattered by in-vitro tissue samples is discussed. The eccentricity and the azimuth angle of local polarization ellipses retrieved for various positions of the focused laser beam on the tissue surface, and the coefficient of collimated transmittance are considered as the diagnostic parameters for differentiation. The experimental data obtained with the psoriasis, discoid lupus erythematosus, alopecia, lichen planus, scabies, demodex, and normal skin samples are presented.

  12. Effect of Dzyaloshinski-Moriya interaction on elastic small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Michels, Andreas; Mettus, Denis; Honecker, Dirk; Metlov, Konstantin L.

    2016-08-01

    For magnetic materials containing many lattice imperfections (e.g., nanocrystalline magnets), the relativistic Dzyaloshinski-Moriya (DM) interaction may result in nonuniform spin textures due to the lack of inversion symmetry at interfaces. Within the framework of the continuum theory of micromagnetics, we explore the impact of the DM interaction on the elastic magnetic small-angle neutron scattering (SANS) cross section. It is shown that the DM interaction gives rise to a polarization-dependent asymmetric term in the spin-flip SANS cross section. Analysis of this feature may provide a means to determine the DM constant.

  13. Imaging method based on attenuation, refraction and ultra-small-angle-scattering of x-rays

    DOEpatents

    Wernick, Miles N.; Chapman, Leroy Dean; Oltulu, Oral; Zhong, Zhong

    2005-09-20

    A method for detecting an image of an object by measuring the intensity at a plurality of positions of a transmitted beam of x-ray radiation emitted from the object as a function of angle within the transmitted beam. The intensity measurements of the transmitted beam are obtained by a crystal analyzer positioned at a plurality of angular positions. The plurality of intensity measurements are used to determine the angular intensity spectrum of the transmitted beam. One or more parameters, such as an attenuation property, a refraction property and a scatter property, can be obtained from the angular intensity spectrum and used to display an image of the object.

  14. Study of Nano-Precipitates Using Small-Angle Neutron Scattering

    SciTech Connect

    Chen, Wei-Ren

    2008-01-01

    Small-Angle-Neutron-Scattering (SANS) experiments were performed on a Ni-based nano-precipitate strengthened superalloy. A theoretical model for SANS absolute intensity distribution, I(Q), was developed to extract the structural properties. During the deformation process, a change in the morphology of precipitates was discovered. However, the average inter-precipitate distance and the average volume of precipitate were found to remain invariant. This microstructural information resolved by SANS is in good agreement with the results obtained from the quantitative transmission-electron-microscopy (TEM) image analysis.

  15. 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.

  16. DAMMIF, a program for rapid ab-initio shape determination in small-angle scattering

    PubMed Central

    Franke, Daniel; Svergun, Dmitri I.

    2009-01-01

    DAMMIF, a revised implementation of the ab-initio shape-determination program DAMMIN for small-angle scattering data, is presented. The program was fully rewritten, and its algorithm was optimized for speed of execution and modified to avoid limitations due to the finite search volume. Symmetry and anisometry constraints can be imposed on the particle shape, similar to DAMMIN. In equivalent conditions, DAMMIF is 25–40 times faster than DAMMIN on a single CPU. The possibility to utilize multiple CPUs is added to DAMMIF. The application is available in binary form for major platforms.

  17. Study of chemically unfolded β-casein by means of small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Aschi, Adel; Gharbi, Abdelhafidh; Daoud, Mohamed; Douillard, Roger; Calmettes, Patrick

    2007-01-01

    β-casein is a flexible amphiphilic milk protein which forms an unfolded conformation in presence of very high denaturant concentrations. The structure of β-casein formed at the bulk was studied by small-angle neutron scattering (SANS). The value of the second virial coefficient of the protein solutions indicates that the interactions between the polypeptide chain and solvent are repulsive. The protein conformation is similar to an excluded volume chain. The corresponding values of the contour length, L, the statistical length, b and the apparent radius of the chain cross-section, Rc are given.

  18. Wide-angle X-ray scattering study of heat-treated PEEK and PEEK composite

    NASA Technical Reports Server (NTRS)

    Cebe, Peggy; Lowry, Lynn; Chung, Shirley Y.; Yavrouian, Andre; Gupta, Amitava

    1987-01-01

    Samples of poly(etheretherketone) (PEEK) neat resin and APC-2 carbon fiber composite were subjected to various heat treatments, and the effect of quenching and annealing treatments was studied by wide-angle X-ray scattering. It is found that high-temperature treatments may introduce disorder into neat resin and composite PEEK when followed by rapid cooling. The disorder is metastable and can revert to ordered state when the material is heated above its glass transition temperature and then cooled slowly. The disorder may result from residual thermal stresses.

  19. Planar laser light scattering technique for measurement of nonspherical particles

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Woo; Choi, Man Soo; Jeong, Dae Hwa; Lee, Hyo Hyung

    2004-09-01

    Small particles are one of the biggest sources that cause loss in semiconductor and flat panel display industry. Therefore, it is important to control them during their manufacturing process. To achieve this goal, exact measurement of particles is first required. Laser light scattering is the most widely used technique for diagnosis of particles because it does not disturb flow field and enables real time and spatially resolved analysis. Measurement of nonspherical aggregates comprised of small primary particles is difficult compared with spherical particles because they have very complex morphology. In addition, most researches on aggregates using light scattering are limited to point measurement, which requires much time to inspect large area and is difficult to observe unsteady phenomenon. Motivated by this, we have developed a laser light scattering method for simultaneous measurement of spatial distributions of aggregate size and morphology. Silica aggregates that were generated in Methane/air premixed flame were used as test particles. Multiangular planar light scattering measurement was carried out using a sheet beam of Ar ion laser and an intensified charge coupled device (ICCD) camera as a light source and a detector, respectively. The result was interpreted based on the Rayleigh-Debye-Gans scattering theory for fractal aggregates to obtain the mean radius of gyration and fractal dimension that are the parameters characterizing aggregate size and morphology. The suitability of our new technique was confirmed by experiment using conventional light scattering.

  20. 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.

  1. Probing the conformation of FhaC with small-angle neutron scattering and molecular modeling.

    PubMed

    Gabel, Frank; Lensink, Marc F; Clantin, Bernard; Jacob-Dubuisson, Françoise; Villeret, Vincent; Ebel, Christine

    2014-07-01

    Probing the solution structure of membrane proteins represents a formidable challenge, particularly when using small-angle scattering. Detergent molecules often present residual scattering contributions even at their match point in small-angle neutron scattering (SANS) measurements. Here, we studied the conformation of FhaC, the outer-membrane, β-barrel transporter of the Bordetella pertussis filamentous hemagglutinin adhesin. SANS measurements were performed on homogeneous solutions of FhaC solubilized in n-octyl-d17-βD-glucoside and on a variant devoid of the α helix H1, which critically obstructs the FhaC pore, in two solvent conditions corresponding to the match points of the protein and the detergent, respectively. Protein-bound detergent amounted to 142 ± 10 mol/mol as determined by analytical ultracentrifugation. By using molecular modeling and starting from three distinct conformations of FhaC and its variant embedded in lipid bilayers, we generated ensembles of protein-detergent arrangement models with 120-160 detergent molecules. The scattered curves were back-calculated for each model and compared with experimental data. Good fits were obtained for relatively compact, connected detergent belts, which occasionally displayed small detergent-free patches on the outer surface of the β barrel. The combination of SANS and modeling clearly enabled us to infer the solution structure of FhaC, with H1 inside the pore as in the crystal structure. We believe that our strategy of combining explicit atomic detergent modeling with SANS measurements has significant potential for structural studies of other detergent-solubilized membrane proteins. PMID:24988353

  2. Probing the Conformation of FhaC with Small-Angle Neutron Scattering and Molecular Modeling

    PubMed Central

    Gabel, Frank; Lensink, Marc F.; Clantin, Bernard; Jacob-Dubuisson, Françoise; Villeret, Vincent; Ebel, Christine

    2014-01-01

    Probing the solution structure of membrane proteins represents a formidable challenge, particularly when using small-angle scattering. Detergent molecules often present residual scattering contributions even at their match point in small-angle neutron scattering (SANS) measurements. Here, we studied the conformation of FhaC, the outer-membrane, β-barrel transporter of the Bordetella pertussis filamentous hemagglutinin adhesin. SANS measurements were performed on homogeneous solutions of FhaC solubilized in n-octyl-d17-βD-glucoside and on a variant devoid of the α helix H1, which critically obstructs the FhaC pore, in two solvent conditions corresponding to the match points of the protein and the detergent, respectively. Protein-bound detergent amounted to 142 ± 10 mol/mol as determined by analytical ultracentrifugation. By using molecular modeling and starting from three distinct conformations of FhaC and its variant embedded in lipid bilayers, we generated ensembles of protein-detergent arrangement models with 120–160 detergent molecules. The scattered curves were back-calculated for each model and compared with experimental data. Good fits were obtained for relatively compact, connected detergent belts, which occasionally displayed small detergent-free patches on the outer surface of the β barrel. The combination of SANS and modeling clearly enabled us to infer the solution structure of FhaC, with H1 inside the pore as in the crystal structure. We believe that our strategy of combining explicit atomic detergent modeling with SANS measurements has significant potential for structural studies of other detergent-solubilized membrane proteins. PMID:24988353

  3. Critical dimension small angle X-ray scattering measurements of FinFET and 3D memory structures

    NASA Astrophysics Data System (ADS)

    Settens, Charles; Bunday, Benjamin; Thiel, Brad; Kline, R. Joseph; Sunday, Daniel; Wang, Chengqing; Wu, Wen-li; Matyi, Richard

    2013-04-01

    We have demonstrated that transmission critical dimension small angle X-ray scattering (CD-SAXS) provides high accuracy and precision CD measurements on advanced 3D microelectronic architectures. The competitive advantage of CD-SAXS over current 3D metrology methods such as optical scatterometry is that CD-SAXS is able to decouple and fit cross-section parameters without any significant parameter cross-correlations. As the industry aggressively scales beyond the 22 nm node, CD-SAXS can be used to quantitatively measure nanoscale deviations in the average crosssections of FinFETs and high-aspect ratio (HAR) memory devices. Fitting the average cross-section of 18:1 isolated HAR contact holes with an effective trapezoid model yielded an average pitch of 796.9 +/- 0.4 nm, top diameter of 70.3 +/- 0.9 nm, height of 1088 +/- 4 nm, and sidewall angle below 0.1°. Simulations of dense 40:1 HAR contact holes and FinFET fin-gate crossbar structures have been analyzed using CD-SAXS to inquire the theoretical precision of the technique to measure important process parameters such as fin CD, height, and sidewall angle; BOX etch recess, thickness of hafnium oxide and titanium nitride layers; gate CD, height, and sidewall angle; and hafnium oxide and titanium nitride etch recess. The simulations of HAR and FinFET structures mimic the characteristics of experimental data collected at a synchrotron x-ray source. Using the CD-SAXS simulator, we estimate the measurement capabilities for smaller similar structures expected at future nodes to predict the applicability of this technique to fulfill important CD metrology needs.

  4. Characterization of Sol-gel Encapsulated Proteins using Small-angle Neutron Scattering

    SciTech Connect

    Luo, Guangming; Zhang, Qiu; Del Castillo, Alexis Rae; Urban, Volker S; O'Neill, Hugh Michael

    2009-01-01

    Entrapment of biomolecules in silica-derived sol-gels has grown into a vibrant area of research since it was originally demonstrated. However, accessing the consequences of entrapment on biomolecules and the gel structure remains a major challenge in characterizing these biohybrid materials. We present the first demonstration that it is possible with small-angle neutron scattering (SANS) to study the conformation of dilute proteins that are entrapped in transparent and dense sol-gels. Using deuterium-labeled green fluorescent protein (GFP) and SANS with contrast variation, we demonstrate that the scattering signatures of the sol-gel and the protein can be separated. Analysis of the scattering curves of the sol-gels using a mass-fractal model shows that the size of the colloidal silica particles and the fractal dimensions of the gels were similar in the absence and presence of protein, demonstrating that GFP did not influence the reaction pathway for the formation of the gel. The major structural difference in the gels was that the pore size was increased 2-fold in the presence of the protein. At the contrast match point for silica, the scattering signal from GFP inside the gel became distinguishable over a wide q range. Simulated scattering curves representing a monomer, end-to-end dimer, and parallel dimer of the protein were calculated and compared to the experimental data. Our results show that the most likely structure of GFP is that of an end-to-end dimer. This approach can be readily applied and holds great potential for the structural characterization of complex biohybrid and other materials.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Grazing incidence small angle X-ray scattering study of silver nanoparticles in ion-exchanged glasses

    NASA Astrophysics Data System (ADS)

    Cheng, Weidong; Wu, Zhaojun; Gu, Xiaohua; Xing, Xueqing; Mo, Guang; Wu, Zhonghua

    2015-05-01

    The size and distribution of silver nanoparticles in ion-exchanged silicate glass induced by thermal treatments in air at different temperatures were investigated by means of grazing incidence small angle X-ray scattering technique, X-ray diffraction and optical absorption spectra. Silver-sodium ion exchange of soda-lime silicate glasses was done at 350 °C for 240 min, then the samples were treated by thermal annealing in air at different temperatures 400, 500 and 550 °C, respectively, for 1 h. After the annealing treatment above 400 °C for 1 h, smaller Ag nanoparticles occurred, together with bigger ones. Both dissolution of smaller Ag nanoparticles and diffusion of larger ones are discussed in these stages of annealing in this contribution.

  10. 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

  11. 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.

  12. Accounting for Observed Small Angle X-ray Scattering Profile in the Protein-Protein Docking Server ClusPro

    PubMed Central

    Xia, Bing; Mamonov, Artem; Leysen, Seppe; Allen, Karen N; Strelkov, Sergei V.; Paschalidis, Ioannis Ch.; Vajda, Sandor; Kozakov, Dima

    2015-01-01

    The protein-protein docking server ClusPro is used by thousands of laboratories, and models built by the server have been reported in over 300 publications. Although the structures generated by the docking include near-native ones for many proteins, selecting the best model is difficult due to the uncertainty in scoring. Small Angle X-ray Scattering (SAXS) is an experimental technique for obtaining low resolution structural information in solution. While not sufficient on its own to uniquely predict complex structures, accounting for SAXS data improves the ranking of models and facilitates the identification of the most accurate structure. Although SAXS profiles are currently available only for a small number of complexes, due to its simplicity the method is becoming increasingly popular. Since combining SAXS experiments will provide a viable strategy for fairly high-throughput determination of protein complex structures, the option of using SAXS restraints is added to the ClusPro server. PMID:26095982

  13. EDITORIAL Proceedings of the XIV International Conference on Small-Angle Scattering, SAS-2009

    NASA Astrophysics Data System (ADS)

    Ungar, Goran; Heenan, Richard

    2010-10-01

    There are 52 papers in these Proceedings. The papers are divided into 10 thematic sections and a section for invited papers and reviews. The sections and the respective section editors are given below. Section Editor(s) Invited Papers and Reviews Peter Griffiths, Wim Bras, Rudolf Winter Beamlines and Instrumentation Elliot Gilbert, Wim Bras, Nigel Rhodes Theory, Data processing and Modelling Jan Skov Pedersen, Carlo Knupp Biological Systems and Membranes Richard Heenan, Cameron Neylon Ceramics, Glasses and Porous Materials Rudolf Winter Colloids and Solutions Peter Griffiths Hierarchical Structures and Fibres Steve Eichhorn, Karen Edler Metallic and Magnetic Systems Armin Hoell Polymers Patrick Fairclough Time resolved Diffraction, Kinetic and Dynamical Studies João Cabral, Christoph Rau We are grateful to all section editors and the many anonymous referees for their invaluable effort which made the publication of the Proceedings possible. The refereeing process was strict and thorough, some papers were rejected and most were improved. The resulting compendium gives a good overview of recent developments in small-angle X-ray and neutron scattering theory, application, methods of analysis and instrumentation. Thus it should be a useful source of reference for a number of years to come. The papers are a good reflection of the material presented at the meeting. Because of the general high quality of the articles, it was difficult to decide which to highlight and be fair to all contributors. The following in particular have caught the attention of the editors. Highlighted papers A statistical survey of publications reporting the application of SAXS and SANS by Aldo Craievich (paper 012003) is recommended reading for anyone needing convincing about the vibrancy of this scientific field and the ever expanding use of these techniques. Two aspects of coherent X-ray scattering, made available by the advent of the 3rd generation synchrotron sources, are discussed in the

  14. 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.

  15. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    SciTech Connect

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    Water’s behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (α{sub p}) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated α{sub p} peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

  16. 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.

  17. 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

  18. Magnetization processes in nanostructured metals and small-angle neutron scattering

    SciTech Connect

    Loeffler, J.F.; Braun, H.B.; Wagner, W.; Kostorz, G.; Wiedenmann, A.

    2005-04-01

    The magnetization process in nanostructured (n-) Fe and Co was investigated via small-angle neutron scattering (SANS). In a zero field, the magnetization exhibits correlations extending over several grains. In intermediate applied magnetic fields around 1 kOe, n-Fe and n-Co samples with small grain sizes exhibit an anisotropic scattering profile with an unusual intensity enhancement for scattering vectors parallel to the field direction. Comparing the experimental data with a modeled granular microstructure containing magnetic domains of arbitrary size and orientation, we conclude that magnetic domains extending over several grains are tilted considerably out of the external field direction in intermediate fields. Since the domain size does not change significantly with the magnitude of the external field, we conclude that the magnetization process does not proceed via domain-wall motion. Together with theoretical arguments showing the existence of marginally stable domains within the random-anisotropy model, our SANS data suggests that the magnetization process proceeds by simultaneous reversal of a few adjacent domains, presumably in the form of small avalanches. This resembles the magnetization process predicted for random-field Ising magnets. Our theoretical analysis of SANS data is general and applies to other systems consisting of magnetic nanoclusters embedded in a nonmagnetic matrix.

  19. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    SciTech Connect

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    The behavior of water near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. Moreover, by monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (alpha(p)) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. Additionally, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated ap peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

  20. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    DOE PAGES

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    The behavior of water near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. Moreover, by monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed thatmore » the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (alpha(p)) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. Additionally, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated ap peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.« less

  1. 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.

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

    DOE PAGES

    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 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

  3. Computation of doses for large-angle Coulomb scattering of proton pencil beams.

    PubMed

    Ciangaru, George; Sahoo, Narayan; Zhu, X Ronald; Sawakuchi, Gabriel O; Gillin, Michael T

    2009-12-21

    In this work we present a study of the impact of considering higher order terms in Molière's multiple Coulomb scattering (MCS) theory for the purpose of calculating scanning proton pencil beam lateral dose profiles in water. The proton beam profile in air, just before entering the target medium, was modeled with a sum of Gaussians fitted with measured data. The subsequent proton scattering in water was described using the three-term Molière distribution, which covers both small- and large-angle scatterings. We compared measured and computed lateral dose profiles at the 2 cm and at the near-Bragg peak depths for proton pencil beams with energies of 72.5 MeV, 121.2 MeV, 163.9 MeV and 221.8 MeV. At shallow depths, the Coulomb interaction model provided a good description of the profiles for all energies, except for 221.8 MeV. At the near-Bragg peak depths, the Coulomb interaction model provided a good description of the profiles only for the 72.5 MeV. The observed discrepancies may be attributed to the additional contributions from nuclear interactions, which may be quantified only after an accurate description of the MCS. The analysis presented in this work did not require user-adjustable parameters and may be carried out in a similar way for any other media, depths and proton energies.

  4. BACKWARD ANGLE STRUCTURE IN THE 20Ne+28Si QUASIELASTIC SCATTERING

    NASA Astrophysics Data System (ADS)

    Sgouros, O.; Soukeras, V.; Pakou, A.; Patronis, N.; Zerva, K.; Keeley, N.; Strojek, I.; Trzcińska, A.; Piasecki, E.; Rusek, K.; Stiliaris, E.; Mazzocco, M.

    2013-10-01

    New data for the quasielastic scattering of 20Ne from a 28Si target at incident energies of 42.5 MeV and 52.3 MeV and for the 28Si(20Ne, 24Mg)24Mg, 28Si(20Ne, 16O)32S and 28Si(20Ne, 12C)36Ar transfer reactions at 52.3 MeV are reported. Oscillations are observed in the backward angle quasielastic scattering data at 52.3 MeV and the 28Si(20Ne, 12C)36Ar transfer cross-sections are of the same magnitude as those for single-α stripping. Coupled reaction channels (CRC) calculations are unable to describe either the quasielastic or the 28Si(20Ne, 12C)36Ar transfer data assuming a sequential α transfer process with α-particle form factors from the literature. The addition of direct 8Be cluster transfer can provide a reasonable description of both data sets, but only with much larger spectroscopic factors than suggested by simple structure calculations or the large 8Be emission thresholds of 20Ne, 28Si and 36Ar, suggesting that the observed structure is of resonance-like origin. An optical model analysis of the quasielastic scattering data is also reported.

  5. Quasielastic small-angle neutron scattering from heavy water solutions of cyclodextrins.

    PubMed

    Kusmin, André; Lechner, Ruep E; Saenger, Wolfram

    2011-01-14

    We present a model for quasielastic neutron scattering (QENS) by an aqueous solution of compact and inflexible molecules. This model accounts for time-dependent spatial pair correlations between the atoms of the same as well as of distinct molecules and includes all coherent and incoherent neutron scattering contributions. The extension of the static theory of the excluded volume effect [A. K. Soper, J. Phys.: Condens. Matter 9, 2399 (1997)] to the time-dependent (dynamic) case allows us to obtain simplified model expressions for QENS spectra in the low Q region in the uniform fluid approximation. The resulting expressions describe the quasielastic small-angle neutron scattering (QESANS) spectra of D(2)O solutions of native and methylated cyclodextrins well, yielding in particular translational and rotational diffusion coefficients of these compounds in aqueous solution. Finally, we discuss the full potential of the QESANS analysis (that is, beyond the uniform fluid approximation), in particular, the information on solute-solvent interactions (e.g., hydration shell properties) that such an analysis can provide, in principle.

  6. Small-angle neutron-scattering study of triglyceride solubilization by lecithin micelles: A direct observation of rod-to-sphere transition

    SciTech Connect

    Lin, Tsanglang; Chen, Sowhsin ); Gabriel, N.E.; Roberts, M.F. )

    1990-01-25

    The solubilization of tributyrin by rodlike diheptanoylphosphatidylcholine (diheptanoyl-PC) micelles has been studied by small-angle neutron-scattering techniques. A rod to sphere transition is observed from the measured angular distribution of neutron-scattering intensities. The transition is from the rodlike micelle to a globular mixed micelle which has tributyrin molecules at the core surrounded by an outer shell of diheptanoyl-PC molecules. When the molar ratio of tributyrin to diheptanoyl-PC is increased beyond 0.18, all rodlike diheptanoyl-PC micelles are transformed into globular mixed micelles. The size of these globular mixed micelles increases with increasing tributyrin concentration in the simple micelle region up to the solubility limit. The small-angle neutron scattering data were analyzed to obtain the structural parameters of the mixed micelles. It is found that the growth of the mixed micelles does not follow a constant available surface area model or a constant palisade layer thickness model. If the model is modified to include tributyrin molecules at the surface of the mixed micelle, the growth behavior can be explained. For the tributyrin/diheptanoyl-PC molar ratio less than 0.18, rodlike micelles are found to coexist with globular mixed micelles. By fitting the neutron scattering data in the middle Q range, it is possible to determine the size and number density of the mixed micelles in the coexistence region. The results of analyzing the small-angle neutron scattering data in the coexistence region. The results of analyzing the small-angle neutron scattering data in the coexistence region show that some tributyrin molecules are solubilized by the rodlike dipheptanoyl-PC micelles and only part of the added tributyrin forms globular micelles.

  7. Molecular dynamics simulation analysis of small-angle neutron scattering by a solution of stearic acid in benzene

    NASA Astrophysics Data System (ADS)

    Eremin, R. A.; Kholmurodov, Kh. T.; Petrenko, V. I.; Rosta, L.; Avdeev, M. V.

    2014-01-01

    Data of small-angle neutron scattering by a diluted solution of stearic acid in deuterated benzene have been analyzed using the results of molecular dynamics simulation. The molecular dynamics simulation approach has been used to calculate the time-averaged distribution of the neutron scattering length density at the interface between the acid molecule and the solvent. It has been shown that the organization of the solvent at the interface with the acid molecule leads to a modulation of the neutron scattering length density and makes a significant contribution to the scattering. This contribution should be taken into account when interpreting the experimental small-angle neutron scattering curves for both the considered system and its analogues.

  8. Methods for magnetic resonance analysis using magic angle technique

    DOEpatents

    Hu, Jian Zhi; Wind, Robert A.; Minard, Kevin R.; Majors, Paul D.

    2011-11-22

    Methods of performing a magnetic resonance analysis of a biological object are disclosed that include placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. In particular embodiments the method includes pulsing the radio frequency to provide at least two of a spatially selective read pulse, a spatially selective phase pulse, and a spatially selective storage pulse. Further disclosed methods provide pulse sequences that provide extended imaging capabilities, such as chemical shift imaging or multiple-voxel data acquisition.

  9. Polarized light scattering technique for morphological characterization of waterborne pathogens

    NASA Astrophysics Data System (ADS)

    Devarakonda, Venkat V.; Manickavasagam, Sivakumar

    2009-05-01

    We have recently developed an elliptically polarized light scattering (EPLS) technique to characterize the morphology of fine particles suspended in an optically non-absorbing medium such as water. This technique provides the size distribution, shape and agglomeration characteristics of suspended particles. This technique can be used to detect various types of biological pathogens such as bacteria, protozoa and viruses in potable water systems. Here we report results obtained from EPLS measurements on two strains of Bacillus spores suspended in water along with comparison with electron microscopy.

  10. Signal, noise, and resolution in correlated fluctuations from snapshot small-angle x-ray scattering

    SciTech Connect

    Kirian, Richard A.; Schmidt, Kevin E.; Wang Xiaoyu; Doak, R. Bruce; Spence, John C. H.

    2011-07-15

    It has been suggested that the three-dimensional structure of one particle may be reconstructed using the scattering from many identical, randomly oriented copies ab initio, without modeling or a priori information. This may be possible if these particles are frozen in either space or time, so that the conventional two-dimensional small-angle x-ray scattering (SAXS) distribution contains fluctuations and is no longer isotropic. We consider the magnitude of the correlated fluctuation SAXS (CFSAXS) signal for typical x-ray free-electron laser (XFEL) beam conditions and compare this against the errors derived with the inclusion of Poisson photon counting statistics. The resulting signal-to-noise ratio (SNR) is found to rapidly approach a limit independent of the number of particles contributing to each diffraction pattern, so that the addition of more particles to a ''single-particle-per-shot'' experiment may be of little value, apart from reducing solvent background. When the scattering power is significantly less than one photon per particle per Shannon pixel, the SNR grows in proportion to incident flux. We provide simulations for protein molecules in support of these analytical results, and discuss the effects of solvent background scatter. We consider the SNR dependence on resolution and particle size, and discuss the application of the method to glasses and liquids, and the implications of more powerful XFELs, smaller focused beams, and higher pulse repetition rates for this approach. We find that an accurate CFSAXS measurement may be acquired to subnanometer resolution for protein molecules if a 9-keV beam containing 10{sup 13} photons is focused to a {approx}100-nm spot diameter, provided that the effects of solvent background can be reduced sufficiently.

  11. Application of GPC/LALLS to cellulose research. [Gel permeation chromatography/low-angle laser light scattering

    SciTech Connect

    Cael, J.J.; Cietek, D.J.; Kolpak, F.J.

    1983-01-01

    The techniques of gel permeation chromatography and low-angle laser light scattering (GPC/LALLS) have been combined for absolute determination of cellulose molecular weights and molecular weight distributions (MWD). The GPC/LALLS technique has been applied to tetrahydrofuran (THF) solutions of cellulose tricarbanilate (CTC) derivatives prepared from celluloses having a wide range of molecular weights. The molecular weight data obtained are consistent with values determined by intrinsic viscosity methods; and as a consequence of the absolute nature of this technique, Mark-Houswink coefficients can be predicted from a single, broad-distribution, linear homopolymer without recourse to tedious and time-consuming fractional precipitation methods. A unique application of the technique has been in correlating GPC/LALLS molecular weight data with the viscosity of nonderivatized celluloses dissolved in 0.5 M cupiethylenediamine hydroxide (CuEn). The procedure yields an absolute viscosity-molecular weight relationship which is comparable with a similar relationship originally derived from cellulose nitrates. The results indicate that the weight-average degree of polymerization (DP/sub w/) for CTC preparations is considerably greater than that obtained from cellulose nitrates, and this discrepancy, in DP/sub w/ has been attributed to errors in the Mark-Houwink coefficients for the cellulose nitrate-acetone system. 25 references, 9 figures, 7 tables.

  12. 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

  13. A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections

    SciTech Connect

    Zhang, You; Yin, Fang-Fang; Ren, Lei; Segars, W. Paul

    2013-12-15

    in estimated and “ground-truth” onboard images for MM-only, FD-only, and MM-FD techniques were 60.10% (±27.17%)/4.9 mm (±3.0 mm), 96.07% (±31.48%)/12.1 mm (±3.9 mm) and 11.45% (±9.37%)/1.3 mm (±1.3 mm), respectively. For orthogonal-view 30°-each scan angle, the corresponding results were 59.16% (±26.66%)/4.9 mm (±3.0 mm), 75.98% (±27.21%)/9.9 mm (±4.0 mm), and 5.22% (±2.12%)/0.5 mm (±0.4 mm). For single-view scan angles of 3°, 30°, and 60°, the results for MM-FD technique were 32.77% (±17.87%)/3.2 mm (±2.2 mm), 24.57% (±18.18%)/2.9 mm (±2.0 mm), and 10.48% (±9.50%)/1.1 mm (±1.3 mm), respectively. For projection angular-sampling-intervals of 0.6°, 1.2°, and 2.5° with the orthogonal-view 30°-each scan angle, the MM-FD technique generated similar VPD (maximum deviation 2.91%) and COMS (maximum deviation 0.6 mm), while sparser sampling yielded larger VPD/COMS. With equal number of projections, the estimation results using scattered 360° scan angle were slightly better than those using orthogonal-view 30°-each scan angle. The estimation accuracy of MM-FD technique declined as noise level increased.Conclusions: The MM-FD technique substantially improves the estimation accuracy for onboard 4D-CBCT using prior planning 4D-CT and limited-angle projections, compared to the MM-only and FD-only techniques. It can potentially be used for the inter/intrafractional 4D-localization verification.

  14. Workshop on Research Techniques in Wave Propagation and Scattering

    NASA Astrophysics Data System (ADS)

    Varadan, V. V.; Varadan, V. K.

    1983-05-01

    A Workshop/Symposium on Research Techniques in Wave Propagation and Scattering was held at the Ohio State University October 18-21, 1982. This workshop was co-sponsored with the generous financial support of the U.S. Army Research Office, U.S. Office of Naval Research, the Center for Welding Research, O.S.U., and the Department of Engineering Mechanics, O.S.U. The workshop format consisted of a core of a general lectures of fifty minutes duration each and several shorter contributions that were of twenty minutes duration each. In addition, there were three panel discussions. The general lectures were of an expository nature on fundamental concepts and basic analytical/numerical techniques for the solution of wave scattering and propagation problems. The speakers were noted for their contribution to these techniques and in many cases have pioneered the techniques that they elaborated upon. These lectures were invaluable to the participants since they were of a pedagogical nature and easily understood by even those not very familiar with the particular method. The written version of many of these lectures will appear in a four volume Handbook on Acoustic, Electromagnetic and Elastic Wave Scattering to be published by North Holland as a separate project.

  15. Development of embedded modulated scatterer technique: Single- and dual-loaded scatterers

    NASA Astrophysics Data System (ADS)

    Donnell, Kristen Marie

    Health monitoring of infrastructure is an important ongoing issue. Therefore, it is important that a cost-effective and practical method for evaluating complex composite structures be developed. A promising microwave-based embedded sensor technology is developed based on the Modulated Scatterer Technique (MST). MST is based on illuminating a probe, commonly a dipole antenna loaded with a PIN diode (also referred to as a single-loaded scatterer, or SLS), with an electromagnetic wave. This impinging wave induces a current along the scatterer length, which causes a scattered field to be reradiated. Modulating the PIN diode also modulates the signal scattered by the probe, resulting in two different states of the probe. By measuring this scattered field, information about the material in the vicinity of the probe may be determined. Using the ratio of both states of the probe removes the dependency of MST on several measurement parameters. In order to separate the scattered signal from reflections from other targets present in the total detected signal, a swept-frequency measurement process and subsequent Fourier Transform (time-gate method) was incorporated into MST. Additionally, a full electromagnetic study of the SLS, as applied to MST, was also conducted. The increased measurement complexity and data processing resulting from the time-gate method prompted the development of a novel dual-loaded scatterer (DLS) probe design, with four possible modulation states. By taking a differential ratio, the reflections from other targets can be effectively removed, while preserving the measurement parameter independence of the SLS ratio. A full electromagnetic derivation and analysis of the capabilities of the DLS as applied to MST is included in this investigation, as well as representative measurements using the DLS probe.

  16. Phase separation and ordering process in Al-Li alloys studied by small-angle neutron scattering and neutron diffraction

    SciTech Connect

    Furusaka, M.; Fujikawa, S.I.; Tranquada, J.M.

    1993-07-01

    To study phase separation kinetics of Al-9.5at.%Li polycrystalline alloys in which precipitates have ordered Al{sub 3}Li ({delta}{prime}) structure, profile analysis of small-angle neutron scattering and superlattice reflections (100) and (110) were done. A small-angle scattering instrument and a triple-axis spectrometer in elastic mode were used in the measurements. Strong texture was observed in the reflections. Therefore, measurements were done using the crystal orientation where the intensity of the reflection was at the maximum. Profiles of small-angle scattering and superlattice reflections were almost identical at higher momentum transfer side. At lower momentum transfer side, small-angle scattering showed interference effects, but superlattice reflection did not show any sign of interference. Integrated intensities of superlattice reflections were obtained and compared with small-angle scattering intensity. The order parameter was not saturated in the {delta}{prime} precipitates at the early stage of the phase separation process.

  17. 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

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

    DOE PAGES

    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 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

  19. 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.).

  20. Peplography: an image restoration technique through scattering media

    NASA Astrophysics Data System (ADS)

    Cho, Myungjin; Cho, Ki-Ok; Kim, Youngjun

    2016-06-01

    In this paper, we propose an image restoration technique through scattering media. Under natural light an imaging through scattering media is a big challenge in many applications. To overcome this challenge, many methods have been reported such as non-invasive imaging, ghost imaging, and wavefront shaping. However, their results have not been sufficient for observers. In this paper, we estimate the scattering media by statistical estimation such as maximum likelihood estimation. By removing this estimated scattering media from the original image, we can obtain the image with only ballistic photons. Then, the ballistic photons can be detected by photon counting imaging concept. In addition, since each basic color channel has its own wavelength, color photon counting process can be implemented. To enhance the visual quality of the result image, a passive three-dimensional (3D) imaging technique such as integral imaging is used. To prove our method and show the better performance, we carried out optical experiments and calculate mean square error (MSE).

  1. Direct detection of resonant electron pitch angle scattering by whistler waves in a laboratory plasma.

    PubMed

    Van Compernolle, B; Bortnik, J; Pribyl, P; Gekelman, W; Nakamoto, M; Tao, X; Thorne, R M

    2014-04-11

    Resonant interactions between energetic electrons and whistler mode waves are an essential ingredient in the space environment, and in particular in controlling the dynamic variability of Earth's natural radiation belts, which is a topic of extreme interest at the moment. Although the theory describing resonant wave-particle interaction has been present for several decades, it has not been hitherto tested in a controlled laboratory setting. In the present Letter we report on the first laboratory experiment to directly detect resonant pitch angle scattering of energetic (∼keV) electrons due to whistler mode waves. We show that the whistler mode wave deflects energetic electrons at precisely the predicted resonant energy, and that varying both the maximum beam energy, and the wave frequency, alters the energetic electron beam very close to the resonant energy.

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

    DOE PAGES

    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 carbonmore » (Do-Do model).« less

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

    SciTech Connect

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

    2009-07-20

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

  4. Ultrasmall-angle X-ray scattering analysis of photonic crystal structure

    SciTech Connect

    Abramova, V. V.; Sinitskii, A. S.; Grigor'eva, N. A.; Grigor'ev, S. V.; Belov, D. V.; Petukhov, A. V.; Mistonov, A. A.; Vasil'eva, A. V.; Tret'yakov, Yu. D.

    2009-07-15

    The results of an ultrasmall-angle X-ray scattering study of iron(III) oxide inverse opal thin films are presented. The photonic crystals examined are shown to have fcc structure with amount of stacking faults varying among the samples. The method used in this study makes it possible to easily distinguish between samples with predominantly twinned fcc structure and nearly perfect fcc stacking. The difference observed between samples fabricated under identical conditions is attributed to random layer stacking in the self-assembled colloidal crystals used as templates for fabricating the inverse opals. The present method provides a versatile tool for analyzing photonic crystal structure in studies of inverse opals made of various materials, colloidal crystals, and three-dimensional photonic crystals of other types.

  5. A new small-angle neutron scattering spectrometer at China Mianyang research reactor

    NASA Astrophysics Data System (ADS)

    Peng, Mei; Sun, Liangwei; Chen, Liang; Sun, Guangai; Chen, Bo; Xie, Chaomei; Xia, Qingzhong; Yan, Guanyun; Tian, Qiang; Huang, Chaoqiang; Pang, Beibei; Zhang, Ying; Wang, Yun; Liu, Yaoguang; Kang, Wu; Gong, Jian

    2016-02-01

    A new pinhole small-angle neutron scattering (SANS) spectrometer, installed at the cold neutron source of the 20 MW China Mianyang Research Reactor (CMRR) in the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, has been put into use since 2014. The spectrometer is equipped with a multi-blade mechanical velocity selector, a multi-beam collimation system, and a two-dimensional He-3 position sensitive neutron detector. The q-range of the spectrometer covers from 0.01 nm-1 to 5.0 nm-1. In this paper, the design and characteristics of the SANS spectrometer are described. The q-resolution calculations, together with calibration measurements of silver behenate and a dispersion of nearly monodisperse poly-methyl-methacrylate nanoparticles indicate that our SANS spectrometer has a good performance and is now in routine service.

  6. Measurement of the absolute differential cross section of proton–proton elastic scattering at small angles

    DOE PAGES

    Mchedlishvili, D.; Chiladze, D.; Dymov, S.; Bagdasarian, Z.; Barsov, S.; Gebel, R.; Gou, B.; Hartmann, M.; Kacharava, A.; Keshelashvili, I.; et al

    2016-02-03

    The differential cross section for proton-proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°-16° to 25°-30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis.more » Furthermore, after extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.« less

  7. Mixed micelles of alkyltrimethylammonium halides A small-angle neutron-scattering study

    NASA Astrophysics Data System (ADS)

    Aswal, V. K.; Goyal, P. S.

    1998-01-01

    Mixed micelles of alkyltrimethylammonium halides have been studied using small-angle neutron scattering (SANS). The experiments were carried out on mixed micellar solutions (CTAB + DTAB, CTAB + TTAB and TTAB + DTAB) of surfactants with the same head group but different chain lengths. The measurements were also made from the mixture of surfactants with the same chain length but different head groups of CTAB + CDAB and CTAB + CTAC. The surfactant components were mixed in the molar proportions of 1:1 and the total concentration was kept 0.2 M. It is found that size, aggregation number and the fractional charge on the micelle in the mixed systems have values in between those for the pure-component systems.

  8. Small angle x-ray scattering studies of carbon anodes used in lithium rechargeable batteries.

    SciTech Connect

    Sandi, G.; Carrado, K. A.; Winans, R. E.; Seifert, S.; Johnson, C. S.

    1999-11-16

    In ANL laboratories, disordered carbons with predictable surface area and porosity properties have been prepared using inorganic templates containing well defined pore sizes. The carbons have been tested in electrochemical cells as anodes in lithium secondary batteries. They deliver high specific capacity and display excellent performance in terms of the number of cycles run. In situ small angle X-ray scattering (SAXS) during electrochemical cycling was carried out at the Advanced Photon Source, at ANL. In order to monitor the carbon electrode structural changes upon cycling, an electrochemical cell was specially designed to allow for the application of electrical current and the collection of SAXS data at the same time. Results show that upon cycling the structure of the carbon remains unchanged, which is desirable in reversible systems.

  9. Small angle neutron and X-ray scattering studies of carbons prepared using inorganic templates

    SciTech Connect

    Sandi, G.; Thiyagarajan, P.; Winans, R.E.; Carrado, K.A.

    1997-09-01

    Small angle neutron (SANS) and X-ray (SAXS) scattering analyses of carbons derived from organic-loaded inorganic template materials, used as anodes in lithium ion cells, have been performed. Two clays were used as templates to load the organic precursors, pillared montmorrillonite (PILC), a layered silicate clay whose sheets have been permanently propped open by sets of thermally stable molecular props, and sepiolite, a natural channeled clay. Five different organic precursors were used to load the PILC: pyrene, styrene, pyrene/trioxane copolymer, ethylene and propylene, whereas only propylene and ethylene were used to load sepiolite. Pyrolysis took place at 700{degrees}C under nitrogen. Values such as hole radius, fractal dimension, cutoff length and density of the final carbons will be compared as a function of the clay and carbon precursors.

  10. Small angle neutron scattering analysis of novel carbons for lithium secondary batteries.

    SciTech Connect

    Sandi, G.; Thiyagarajan, P.; Winans, R.; Carrado, K.

    1998-01-14

    Small angle neutron scattering analyses of carbonaceous materials used as anodes in lithium ion cells have been performed. The carbons have been synthesized using pillared clays (PILCs) as inorganic templates. Pillared clays are layered silicates whose sheets have been permanently propped open by sets of thermally stable molecular props. The calcined PILC was loaded with five different organic precursors and heated at 700 C under nitrogen. When the inorganic pillars were removed by acid treatment, carbon sheets are produced with holes. The fitting of the data in the high q region suggested that the carbon sheets have voids with radii ranging from 4 to 8 {angstrom}. Similar radii were obtained for the PILC and PILC/organic precursor, which suggests that the carbon was well distributed in the clay prior to pyrolysis.

  11. The complete VS ribozyme in solution studied by small-angle X-ray scattering

    SciTech Connect

    Lipfert, Jan; Ouellet, Jonathan; Norman, David G.; Doniach, Sebastian; Lilley, David M.J.

    2008-10-06

    We have used small-angle X-ray solution scattering to obtain ab initio shape reconstructions of the complete VS ribozyme. The ribozyme occupies an electron density envelope with an irregular shape, into which helical sections have been fitted. The ribozyme is built around a core comprising a near-coaxial stack of three helices, organized by two three-way helical junctions. An additional three-way junction formed by an auxiliary helix directs the substrate stem-loop, juxtaposing the cleavage site with an internal loop to create the active complex. This is consistent with the current view of the probable mechanism of trans-esterification in which adenine and guanine nucleobases contributed by the interacting loops combine in general acid-base catalysis.

  12. NUMERICAL ANALYSIS OF THE FOKKER-PLANCK EQUATION WITH ADIABATIC FOCUSING: ISOTROPIC PITCH-ANGLE SCATTERING

    SciTech Connect

    Danos, Rebecca J.; Fiege, Jason D.; Shalchi, Andreas E-mail: fiege@physics.umanitoba.ca

    2013-07-20

    We present numerical solutions to both the standard and modified two-dimensional Fokker-Planck equations with adiabatic focusing and isotropic pitch-angle scattering. With the numerical solution of the particle distribution function, we then discuss the related numerical issues, calculate the parallel diffusion coefficient using several different methods, and compare our numerical solutions for the parallel diffusion coefficient to the analytical forms derived earlier. We find the numerical solution to the diffusion coefficient for both the standard and modified Fokker-Planck equations agrees with that of Shalchi for the mean squared displacement method of computing the diffusion coefficient. However, we also show the numerical solution agrees with that of Litvinenko and Shalchi and Danos when calculating the diffusion coefficient via the velocity correlation function.

  13. PITCH-ANGLE SCATTERING: RESONANCE VERSUS NONRESONANCE, A BASIC TEST OF THE QUASILINEAR DIFFUSIVE RESULT

    SciTech Connect

    Ragot, B. R.

    2012-01-01

    Due to the very broad range of the scales available for the development of turbulence in space and astrophysical plasmas, the energy at the resonant scales of wave-particle interaction often constitutes only a tiny fraction of the total magnetic turbulent energy. Despite the high efficiency of resonant wave-particle interaction, one may therefore question whether resonant interaction really is the determining interaction process between particles and turbulent fields. By evaluating and comparing resonant and nonresonant effects in the frame of a quasilinear calculation, the dominance of resonance is here put to the test. By doing so, a basic test of the classical resonant quasilinear diffusive result for the pitch-angle scattering of charged energetic particles is also performed.

  14. The complete VS ribozyme in solution studied by small-angle X-ray scattering

    PubMed Central

    Lipfert, Jan; Ouellet, Jonathan; Norman, David G.; Doniach, Sebastian; Lilley, David M.J.

    2010-01-01

    SUMMARY We have used small-angle X-ray solution scattering to obtain ab initio shape reconstructions of the complete VS ribozyme. The ribozyme occupies an electron density envelope with an irregular shape, into which helical sections have been fitted. The ribozyme is built around a core comprising a near-coaxial stack of three helices, organized by two three-way helical junctions. An additional three-way junction formed by an auxiliary helix directs the substrate stem-loop, juxtaposing the cleavage site with an internal loop to create the active complex. This is consistent with the current view of the probable mechanism of transesterification in which adenine and guanine nucleobases contributed by the interacting loops combine together in general acid-base catalysis. PMID:18786398

  15. Towards weighing individual atoms by high-angle scattering of electrons.

    PubMed

    Argentero, G; Mangler, C; Kotakoski, J; Eder, F R; Meyer, J C

    2015-04-01

    We consider theoretically the energy loss of electrons scattered to high angles when assuming that the primary beam can be limited to a single atom. We discuss the possibility of identifying the isotopes of light elements and of extracting information about phonons in this signal. The energy loss is related to the mass of the much heavier nucleus, and is spread out due to atomic vibrations. Importantly, while the width of the broadening is much larger than the energy separation of isotopes, only the shift in the peak positions must be detected if the beam is limited to a single atom. We conclude that the experimental case will be challenging but is not excluded by the physical principles as far as considered here. Moreover, the initial experiments demonstrate that the separation of gold and carbon based on a signal that is related to their mass, rather than their atomic number.

  16. 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.

  17. Waveguide detection of right-angle-scattered light in flow cytometry

    DOEpatents

    Mariella, Jr., Raymond P.

    2000-01-01

    A transparent flow cell is used as an index-guided optical waveguide. A detector for the flow cell but not the liquid stream detects the Right-Angle-Scattered (RAS) Light exiting from one end of the flow cell. The detector(s) could view the trapped RAS light from the flow cell either directly or through intermediate optical light guides. If the light exits one end of the flow cell, then the other end of the flow cell can be given a high-reflectivity coating to approximately double the amount of light collected. This system is more robust in its alignment than the traditional flow cytometry systems which use imaging optics, such as microscope objectives.

  18. 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.

  19. Adsorption of CO2 in porous MCM-41 and MCM-48 using small angle scattering

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Das, Narayan; Warren, Garfield; Rupp, John; Mastalerz, Maria; Prisk, Timothy; Sokol, Paul

    2012-02-01

    Adsorption of CO2 onto the surface of nanopores in organic rich materials, such as shale and coals, is of great interest for understanding the processes associated with geological sequestration. These natural materials have complex pore structures which make the interpretation of experimental sorption measurements complicated. MCMs are synthetic materials with a well-defined regular porous structure that provides an ideal substrate to evaluate the models for the adsorption of gases (CO2) into nanopores. Samples of MCM-41 and MCM-48 were synthesized at Indiana University and were characterized by nitrogen adsorption isotherms and Small Angle X-ray Scattering (SAXS). SANS studies were carried out on MCMs with different pore sizes as a function of pore filling and the results are interpreted in terms of layer growth models.

  20. 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.

  1. Pauli Limiting and Multi-Band Superconductivity in KFe2As2 Studied by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Eskildsen, M. R.; Kuhn, S. J.; Kawano-Furukawa, H.; Ono, M.; Forgan, E. M.; Jellyman, E.; Riyat, R.; Lee, C. H.; Kihou, K.; Hardy, F.; Wolf, Th.; Meingast, C.; Gavilano, J. L.

    We have studied the intrinsic anisotropy of the superconducting state in KFe2As2, using used small-angle neutron scattering to image the vortex lattice (VL) as the applied magnetic field is rotated towards the FeAs planes. The anisotropy is found to be strongly field dependent, indicating multi-band superconductivity. Furthermore, the high field anisotropy significantly exceeds that of the upper critical field, providing further support for Pauli limiting in KFe2As2 for field applied along the basal plane. Finally, we are able determine the contribution to the field modulation in the mixed state due to Pauli Paramagnetic Effects by measuring both the non-spin flip and spin flip VL scattered intensity. This represents the first instance where all the effects listed above have been obtained simultaneously and in a comprehensive manner by a single experimental technique. This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Award DE-FG02-10ER46783.

  2. 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.

  3. Determination of the Crystallinity of Semicrystalline Poly(3-hexyl thiophene) by Means of Wide Angle X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Balko, Jens; Lohwasser, Ruth; Thelakkat, Mukundan; Sommer, Michael; Pascui, Ovidiu; Saalwaechter, Kay; Thurn-Albrecht, Thomas

    2013-03-01

    Poly(3-hexyl thiophene) (P3HT) is a common polymer semiconductor, often used as material or component in organic field effect transistors or solar cells. The crystallinity of this semicrystalline material is among other parameters governing the electronic mobility. However, at present there is no routine method available to determine an absolute value for the crystallinity, and the values given in the literature e.g. for the enthalpy of melting vary by a factor of three. Wide Angle X-Ray Scattering (WAXS) probes the crystals as well the amorphous parts of the sample. We present an approach for the determination of the crystallinity based on the evaluation of WAXS intensities at low scattering vectors emanating from the amorphous regions. The result is used for a calibration of the melting enthalpy (34 J/g) that can serve as a reference value for more convenient calorimetric techniques and compared to the results of recent NMR investigations. We discuss the crystallinity for a number of chemically well-defined samples, with different molecular weight and a typical commercial sample with broad molecular weight distribution. Despite the high crystallinities of 60 to 80% the crystallites exhibit a large amount of disorder.

  4. NOTE: Characterization of cirrhosis and hepatocellular carcinoma using low-angle x-ray scattering signatures of serum

    NASA Astrophysics Data System (ADS)

    Elshemey, Wael M.; Desouky, Omar S.; Mohammed, Mohammed S.; Elsayed, Anwar A.; El-houseini, Motawa E.

    2003-09-01

    The diagnosis of hepatocellular carcinoma (HCC) usually occurs at late stages in the disease when there are few effective treatment options. The measurement of the concentration of tumour markers in the serum of patients is a complementary tool frequently used for the interpretation of diagnostic imaging results. It is also used as a prognostic tool for the detection of cancer. Unfortunately, the sensitivity of tumour markers is still low and many times it yields normal results for cirrhotic and HCC patients. In the current work, the detection possibility of the structural changes in serum proteins accompanying cirrhosis and HCC is investigated using a low-angle x-ray scattering (LAXS) technique. The results show that there are significant differences in the LAXS profiles of cirrhosis and HCC lyophilized serum samples compared to normal. The changes in shape, total counts and position of the first scattering peak at 4.8°, which was previously reported to be sensitive to the structural changes in protein, showed the most characteristic deviations from normal serum. The present results are promising and would offer a potentially helpful complementary tool for monitoring cirrhosis and HCC.

  5. Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations

    SciTech Connect

    Chen, Chun-Yu; Chen, Wei-Ren; Herwig, Kenneth W; Hong, Kunlun; Li, Xin; Liu, Emily; Liu, Yun; Smith, Gregory Scott; Wu, Bin; Yang, Jun; Do, Changwoo

    2011-01-01

    An experimental scheme using contrast variation small angle neutron scattering technique (SANS), is developed to investigate the structural characteristics of amine-terminated poly(amidoamine) dendrimers (PAMAM) solutions. The focus is placed on understanding the dependence of intra-dendrimer water and polymer distribution on molecular protonation, which can be precisely adjusted by tuning the pH value of solution. Assuming the spherical symmetry in the spatial arrangement of the constituent component of dendrimer, and the atomic ratio of hydrogen-to-deuterium for the solvent residing within the cavities of dendrimer is identical to that for the solvent outside dendrimer, the intra-dendrimer water distribution along the radial direction can be determined based on the model of coherent scattering cross section developed in this work. Moreover, our result clearly reveals an outward relocation of the peripheral groups, as well as the enhanced intra-dendrimer hydration, upon increasing the molecular protonation and therefore allows the determination of segmental backfolding in a quantitative manner. The connection between these charge-induced structural changes and our recently observed progressively active segmental dynamics is also discussed.

  6. A triple axis double crystal multiple reflection camera for ultra small angle X-ray scattering

    NASA Astrophysics Data System (ADS)

    Lambard, Jacques; Lesieur, Pierre; Zemb, Thomas

    1992-06-01

    To extend the domain of small angle X-ray scattering requires multiple reflection crystals to collimate the beam. A double crystal, triple axis X-ray camera using multiple reflection channel cut crystals is described. Procedures for measuring the desmeared scattering cross-section on absolute scale are described as well as the measurement from several typical samples : fibrils of collagen, 0.3 μm diameter silica spheres, 0.16 μm diameter interacting latex spheres, porous lignite coal, liquid crystals in a surfactant-water system, colloidal crystal of 0.32 μm diameter silica spheres. L'extension du domaine de diffusion des rayons-X vers les petits angles demande l'emploi de cristaux à réflexions multiples pour collimater le faisceau. Nous décrivons une caméra à rayons-X à trois axes où les réflexions multiples sont réalisées dans deux cristaux à gorge. Nous donnons ensuite les procédures de déconvolution pour obtenir la section efficace de diffusion en échelle absolue, ainsi que les résultats des mesures effectuées avec plusieurs échantillons typiques : fibres de collagène, sphères de silice de 0,3 μm de diamètre, sphères de latex de 0,16 μm de diamètre en interaction, charbon lignite poreux, cristaux liquides formés dans un système eau-tensioactif, solution colloïdale de sphères de silice de 0,32 μm de diamètre.

  7. Accuracy and efficiency considerations for wide-angle wavefield extrapolators and scattering operators

    NASA Astrophysics Data System (ADS)

    Thomson, C. J.

    2005-10-01

    Several observations are made concerning the numerical implementation of wide-angle one-way wave equations, using for illustration scalar waves obeying the Helmholtz equation in two space dimensions. This simple case permits clear identification of a sequence of physically motivated approximations of use when the mathematically exact pseudo-differential operator (PSDO) one-way method is applied. As intuition suggests, these approximations largely depend on the medium gradients in the direction transverse to the main propagation direction. A key point is that narrow-angle approximations are to be avoided in the interests of accuracy. Another key consideration stems from the fact that the so-called `standard-ordering' PSDO indicates how lateral interpolation of the velocity structure can significantly reduce computational costs associated with the Fourier or plane-wave synthesis lying at the heart of the calculations. A third important point is that the PSDO theory shows what approximations are necessary in order to generate an exponential one-way propagator for the laterally varying case, representing the intuitive extension of classical integral-transform solutions for a laterally homogeneous medium. This exponential propagator permits larger forward stepsizes. Numerical comparisons with Helmholtz (i.e. full) wave-equation finite-difference solutions are presented for various canonical problems. These include propagation along an interfacial gradient, the effects of a compact inclusion and the formation of extended transmitted and backscattered wave trains by model roughness. The ideas extend to the 3-D, generally anisotropic case and to multiple scattering by invariant embedding. It is concluded that the method is very competitive, striking a new balance between simplifying approximations and computational labour. Complicated wave-scattering effects are retained without the need for expensive global solutions, providing a robust and flexible modelling tool.

  8. Structural and Thermodynamic Properties of Septin 3 Investigated by Small-Angle X-Ray Scattering

    PubMed Central

    Ortore, Maria Grazia; Macedo, Joci N.A.; Araujo, Ana Paula U.; Ferrero, Claudio; Mariani, Paolo; Spinozzi, Francesco; Itri, Rosangela

    2015-01-01

    Septins comprise a family of proteins involved in a variety of cellular processes and related to several human pathologies. They are constituted by three structural domains: the N- and C-terminal domains, highly variable in length and composition, and the central domain, involved in the guanine nucleotide (GTP) binding. Thirteen different human septins are known to form heterogeneous complexes or homofilaments, which are stabilized by specific interactions between the different interfaces present in the domains. In this work, we have investigated by in-solution small-angle x-ray scattering the structural and thermodynamic properties of a human septin 3 construct, SEPT3-GC, which contains both of both interfaces (G and NC) responsible for septin-septin interactions. In order to shed light on the role of these interactions, small-angle x-ray scattering measurements were performed in a wide range of temperatures, from 2 up to 56°C, both with and without a nonhydrolysable form of GTP (GTPγS). The acquired data show a temperature-dependent coexistence of monomers, dimers, and higher-order aggregates that were analyzed using a global fitting approach, taking into account the crystallographic structure of the recently reported SEPT3 dimer, PDB:3SOP. As a result, the enthalpy, entropy, and heat capacity variations that control the dimer-monomer dissociation equilibrium in solution were derived and GTPγS was detected to increase the enthalpic stability of the dimeric species. Moreover, a temperature increase was observed to induce dissociation of SEPT3-GC dimers into monomers just preceding their reassembling into amyloid aggregates, as revealed by the Thioflavin-T fluorescence assays. PMID:26083929

  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. 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).

  11. Glycerol monooleate reverse micelles in nonpolar solvents: computer simulations and small-angle neutron scattering.

    PubMed

    Bradley-Shaw, Joshua L; Camp, Philip J; Dowding, Peter J; Lewtas, Ken

    2015-03-19

    The formation of glycerol monooleate reverse micelles in n-heptane and toluene at room temperature is studied using molecular-dynamics simulations and small-angle neutron scattering. The glycerol monooleate concentrations under consideration are in the range of 5-20 wt %. Under these conditions, spontaneous reverse-micelle formation is observed on the simulation timescale (up to 30 ns). From simulations, the typical dimensions (semiaxes) of the equivalent ellipsoids with the same masses and moments of inertia are in the range of 15-23 Å, with instantaneous shapes that are slightly nonspherical. By analyzing the scattering form factors from simulation and experiment, the radii of gyration of the reverse micelles are determined to be approximately 15 Å. The number of glycerol monooleate molecules in a reverse micelle is smaller in toluene (∼20) than in n-heptane (∼30), but the overall dimensions are similar due to greater penetration of the toluene in to the reverse micelle. The effects of low concentrations (1 wt %) of water, acetic acid, and ethanol on the reverse-micelle dimensions are determined. The overall structural effects are small, but the distributions of the molecules within the reverse micelles are shown to be sensitive to the molecular polarity.

  12. Characterization of Physically and Chemically Separated Athabasca Asphaltenes Using Small-Angle X-ray Scattering

    SciTech Connect

    Amundaraín Hurtado, Jesús Leonardo; Chodakowski, Martin; Long, Bingwen; Shaw, John M.

    2012-02-07

    Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS). Two methods were used to separate asphaltenes from the Athabasca bitumen: namely, chemical separation by precipitation with n-pentane and physical separation by nanofiltration using a zirconia membrane with a 20 nm average pore size. The permeate and chemically separated samples were diluted in 1-methylnaphtalene and n-dodecane prior to SAXS measurements. The temperature and asphaltene concentration ranges were 50-310 C and 1-10.4 wt %, respectively. Model-independent analysis of SAXS data provided the radius of gyration and the scattering coefficients. Model-dependent fits provided size distributions for asphaltenes assuming that they are dense and spherical. Model-independent analysis for physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and the temperature dependence of structural properties. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in hydrocarbon resources. While the residuals for model-dependent fits are small, the results are inconsistent with the structural parameters obtained from model-independent analysis.

  13. Determining the melt miscibility of commercial polyolefin blends by Small-Angle Light Scattering

    NASA Astrophysics Data System (ADS)

    Peng, Ping

    2005-03-01

    The melt miscibility of high-density polyethylene (HDPE) (Mw = 52 kg/mol, PDI = 2.9) and linear low-density polyethylenes (LLDPEs) based on homogeneous ethylene-1-butene copolymers (EB0187: 18.7 mol% butene branches, Mw = 58.1 kg/mol and EB0059: 5.9 mol% butene branches, Mw = 70 kg/mol) is determined by Small-Angle Light Scattering (SALS) under parallel-polarized optical alignment. Blends with branching density differences (δy) ranging from 5.9 to 18.7 mol% were studied. For the HDPE/EB0187 blend, (δy = 18.7%), cooling and isothermal measurements (2 h) in the melt can be used to determine the miscibility and the phase boundary. When this blend is rapidly cooled room temperature, the resulting SALS patterns show that the size of phase separated domain (˜ 1 μm) is much smaller than the average spherulite size (68 μm). These results consist with our microscopic observations and the transmitted light measured simultaneously with the VV scattering in the melt. From the compositions studied, we can conclude that this blend exhibits UCST behavior. For blends with lower δy, isothermal measurements provide a sensitive means for determining the melt miscibility. Based on the above observations, we can conclude that SALS can be used to determine the melt miscibility of polyolefin blends.

  14. Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering

    PubMed Central

    Zhang-Haagen, Bo; Biehl, Ralf; Nagel-Steger, Luitgard; Radulescu, Aurel; Richter, Dieter; Willbold, Dieter

    2016-01-01

    Small proteins like amyloid beta (Aβ) monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS) is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP) by using SANS and dynamic light scattering (DLS). We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1–40 and 1.6±0.1 nm for Aβ1–42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1–40 and 3.2±0.4 nm for Aβ1–42 including a surface layer of dHFIP solvent molecules. PMID:26919121

  15. Study of nanoscale structures in hydrated biomaterials using small-angle neutron scattering

    PubMed Central

    Luk, Arnold; Murthy, N. Sanjeeva; Wang, Wenjie; Rojas, Ramiro; Kohn, Joachim

    2012-01-01

    Distribution of water in three classes of biomedically relevant and degradable polymers was investigated using small-angle neutron scattering. In semicrystalline polymers, such as poly(lactic acid) and poly(glycolic acid), water was found to diffuse preferentially into the noncrystalline regions. In amorphous polymers, such as poly(D,L-lactic acid) and poly(lactic-co-glycolic acid), the scattering after 7-days of incubation was attributed to water in microvoids that form following the hydrolytic degradation of the polymer. In amorphous copolymers containing hydrophobic segments (desaminotyrosyl-tyrosine ethyl ester) and hydrophilic blocks (poly(ethylene glycol) PEG), a sequence of distinct regimes of hydration were observed: homogeneous distribution (~ 10 Å length scales) at <13 wt% PEG (~ 1 water per EG), clusters of hydrated domains (~50 Å radius) separated at 24 wt% PEG (1 to 2 water per EG), uniformly distributed hydrated domains at 41 wt% PEG (~ 4 water per EG), and phase inversion at > 50 wt% PEG ( > 6 water per EG ). Increasing PEG content increased the number of these domains with only a small decrease in distance between the domains. These discrete domains appeared to coalesce to form submicron droplets at ~60 °C, above the melting temperature of crystalline PEG. Significance of such observations on the evolution of μm size channels that form during hydrolytic erosion is discussed. PMID:22227373

  16. 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

  17. 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.

  18. Small-Angle Neutron Scattering and Fluorescence Studies of Mixed Surfactants with Dodecyl Tails.

    PubMed

    Griffiths; Whatton; Abbott; Kwan; Pitt; Howe; King; Heenan

    1999-07-01

    The mixed micelles formed in solutions of the anionic surfactant sodium dodecylsulfate (SDS) and the nonionic surfactant dodecylmalono-bis-N-methylglucamide (DBNMG) were studied by surface tension, fluorescence, and small-angle neutron scattering. Measurements of the critical micelle concentration (CMC) by surface tension and fluorescence show that these two surfactants mix nonideally. The experimental values of the CMCs for surfactant mixtures for all compositions are less than the ideal prediction proposed by Clint (J. Chem. Soc. 71, 1327 (1975)). Regular solution theory (for example, Penfold et al., Langmuir 11, 2498 (1995)) can be used to calculate the composition of the micelle at the CMC. The micellar composition thus calculated differs significantly from that at higher total surfactant concentrations, the latter being much closer to the stoichiometric composition. The polarity of the micellar environment, as perceived by a solubilized fluorescence probe, is identical for both the single-component and the mixed micelles. The scattering data show that the mixed micelles are comparable in size to the pure nonionic micelle and slightly larger than the anionic micelle. Parallel studies with deuterated SDS showed no evidence of segregation or local ordering within the mixed micelle. The effective charge on the mixed micelle is determined by the amount of ionic surfactant within the micelle. Addition of 0.1 M NaCl to these systems has no effect on the CMC, micelle ellipticity, and aggregation number-a behavior very different from that observed for simple SDS solutions. Copyright 1999 Academic Press.

  19. Accurate assessment of mass, models and resolution by small-angle scattering

    PubMed Central

    Rambo, Robert P.; Tainer, John A.

    2013-01-01

    Modern small angle scattering (SAS) experiments with X-rays or neutrons provide a comprehensive, resolution-limited observation of the thermodynamic state. However, methods for evaluating mass and validating SAS based models and resolution have been inadequate. Here, we define the volume-of-correlation, Vc: a SAS invariant derived from the scattered intensities that is specific to the structural state of the particle, yet independent of concentration and the requirements of a compact, folded particle. We show Vc defines a ratio, Qr, that determines the molecular mass of proteins or RNA ranging from 10 to 1,000 kDa. Furthermore, we propose a statistically robust method for assessing model-data agreements (X2free) akin to cross-validation. Our approach prevents over-fitting of the SAS data and can be used with a newly defined metric, Rsas, for quantitative evaluation of resolution. Together, these metrics (Vc, Qr, X2free, and Rsas) provide analytical tools for unbiased and accurate macromolecular structural characterizations in solution. PMID:23619693

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-06-01

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

  2. Review of the fundamental theories behind small angle X-ray scattering, molecular dynamics simulations, and relevant integrated application

    PubMed Central

    Boldon, Lauren; Laliberte, Fallon; Liu, Li

    2015-01-01

    In this paper, the fundamental concepts and equations necessary for performing small angle X-ray scattering (SAXS) experiments, molecular dynamics (MD) simulations, and MD-SAXS analyses were reviewed. Furthermore, several key biological and non-biological applications for SAXS, MD, and MD-SAXS are presented in this review; however, this article does not cover all possible applications. SAXS is an experimental technique used for the analysis of a wide variety of biological and non-biological structures. SAXS utilizes spherical averaging to produce one- or two-dimensional intensity profiles, from which structural data may be extracted. MD simulation is a computer simulation technique that is used to model complex biological and non-biological systems at the atomic level. MD simulations apply classical Newtonian mechanics’ equations of motion to perform force calculations and to predict the theoretical physical properties of the system. This review presents several applications that highlight the ability of both SAXS and MD to study protein folding and function in addition to non-biological applications, such as the study of mechanical, electrical, and structural properties of non-biological nanoparticles. Lastly, the potential benefits of combining SAXS and MD simulations for the study of both biological and non-biological systems are demonstrated through the presentation of several examples that combine the two techniques. PMID:25721341

  3. Kinetic small angle neutron scattering of the skyrmion lattice in MnSi

    NASA Astrophysics Data System (ADS)

    Mühlbauer, S.; Kindervater, J.; Adams, T.; Bauer, A.; Keiderling, U.; Pfleiderer, C.

    2016-07-01

    We report a kinetic small angle neutron scattering (SANS) study of the skyrmion lattice (SL) in MnSi. Induced by an oscillatory tilting of the magnetic field direction, the elasticity and relaxation of the SL along the magnetic field direction have been measured with microsecond resolution. For the excitation frequency of 325 {{Hz}} the SL begins to track the tilting motion of the applied magnetic field under tilting angles exceeding {α }{{c}}≳ 0.4^\\circ . Empirically the associated angular velocity of the tilting connects quantitatively with the critical charge carrier velocity of ∼ 0.1 {{mm}} {{{s}}}-1 under current driven spin transfer torques, for which the SL unpins. In addition, a pronounced temperature dependence of the skyrmion motion is attributed to the variation of the skyrmion stiffness. Taken together our study highlights the power of kinetic SANS as a new experimental tool to explore, in a rather general manner, the elasticity and impurity pinning of magnetic textures across a wide parameter space without parasitic signal interferences due to ohmic heating or Oersted magnetic fields.

  4. Pitch Angle Scattering of Ring Current Ions During a Magnetic Storm

    NASA Astrophysics Data System (ADS)

    Walt, M.; Voss, H. D.

    2001-05-01

    On August 6, 1998, a magnetic storm occurred with a minimum Dst of 138 nT. Pitch angle distributions of the ring current ions were obtained with the SEPS/CEPPAD charged particle spectrometer on the NASA POLAR satellite during its passes through the radiation belt region. When SEPS was oriented parallel to the geomagnetic field, SEPS measured the downward and upward ion fluxes inside the loss cones with an angular resolution of about 1.5 deg. During the day following minimum Dst fluxes of 155 keV ions were observed inside the downward loss cone, comparable in intensity to the trapped fluxes measured at equatorial pitch angles of 50 deg. The distributions within the loss cone were uniform, suggesting that strong diffusion was occurring equatorward of the satellite latitude of 45 deg. At L values between 4 and 5 the scattering was strong enough to dominate the losses of ring current ions. During the early recovery phase of the storm the precipitation was greater in the afternoon sector (16:00 MLT) than in the morning sector (4:00 MLT).

  5. Size And Shape of Detergent Micelles Determined By Small-Angle X-Ray Scattering

    SciTech Connect

    Lipfert, Jan; Columbus, Linda; Chu, Vincent B.; Lesley, Scott A.; Doniach, Sebastian; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /SLAC, SSRL /Pasteur Inst., Paris /Scripps Res. Inst. /Novartis Res. Found.

    2009-04-29

    We present a systematic analysis of the aggregation number and shape of micelles formed by nine detergents commonly used in the study of membrane proteins. Small-angle X-ray scattering measurements are reported for glucosides with 8 and 9 alkyl carbons (OG/NG), maltosides and phosphocholines with 10 and 12 alkyl carbons (DM/DDM and FC-10/FC-12), 1,2-dihexanoyl-sn-glycero-phosphocholine (DHPC), 1-palmitoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] (LPPG), and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). The SAXS intensities are well described by two-component ellipsoid models, with a dense outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core. These models provide an intermediate resolution view of micelle size and shape. In addition, we show that Guinier analysis of the forward scattering intensity can be used to obtain an independent and model-free measurement of the micelle aggregation number and radius of gyration. This approach has the advantage of being easily generalizable to protein-detergent complexes, where simple geometric models are inapplicable. Furthermore, we have discovered that the position of the second maximum in the scattering intensity provides a direct measurement of the characteristic head group-head group spacing across the micelle core. Our results for the micellar aggregation numbers and dimensions agree favorably with literature values as far as they are available. We de novo determine the shape of FC-10, FC-12, DM, LPPG, and CHAPS micelles and the aggregation numbers of FC-10 and OG to be ca. 50 and 250, respectively. Combined, these data provide a comprehensive view of the determinants of micelle formation and serve as a starting point to correlate detergent properties with detergent-protein interactions.

  6. 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

  7. Simple technique for the fabrication of a penta prism with high accuracy right angle deviation.

    PubMed

    Chatterjee, Sanjib; Pavan Kumar, Y

    2007-09-10

    What we believe to be a new technique for the fabrication of a penta prism (PP) with high accuracy right angle deviation of the incident beam is presented. We derive simple formulas relating to the error in right angle deviation with the errors in 45 degrees (beta) and 90 degrees (delta) angles of a PP, and we determine error in right angle deviation from the angle ((error in right angle deviation)r) between the plane wavefronts reflected from the right angled surfaces (external Fresnel reflection on the entrance surface and internal Fresnel reflection on the exit surface) of a PP and the angular error (delta) between the same surfaces. The error in right angle deviation is determined from the measurement of (error in right angle deviation)r using an autocollimator and a Fizeau interferometer, and error in right angle deviation is corrected to a high order of accuracy during the final stage of polishing one of the slanted surfaces of the PP. A new technique to determine the magnitude and direction of the small values of (error in right angle deviation)r is proposed and verified. The result for a PP is presented.

  8. Localization of the large-angle foil-scattering beam loss caused by the multiturn charge-exchange injection

    NASA Astrophysics Data System (ADS)

    Kato, Shinichi; Yamamoto, Kazami; Yoshimoto, Masahiro; Harada, Hiroyuki; Kinsho, Michikazu

    2013-07-01

    In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, significant losses were observed at the branching of the H0 dump line and the beam position monitor that was inserted downstream of the H0 dump branch duct. These losses were caused by the large-angle scattering of the injection and circulating beams at the charge-exchange foil. To realize high-power operation, these losses must be mitigated. Therefore, a new collimation system was developed and installed in October 2011. To efficiently optimize this system, the behavior of particles scattered by the foil and produced by the absorber were simulated, and the optimal position and angle of the absorber were investigated. During this process, an angle regulation method for the absorber was devised. An outline of this system, the angle regulation method for the absorber, and the performance of this new collimation system are described.

  9. Multiaxial deformation of polyethylene and polyethylene/clay nanocomposites: In situ synchrotron small angle and wide angle X-ray scattering study

    SciTech Connect

    Gurun, Bilge; Bucknall, David G.; Thio, Yonathan S.; Teoh, Chin Ching; Harkin-Jones, Eileen

    2013-01-10

    A unique in situ multiaxial deformation device has been designed and built specifically for simultaneous synchrotron small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) measurements. SAXS and WAXS patterns of high-density polyethylene (HDPE) and HDPE/clay nanocomposites were measured in real time during in situ multiaxial deformation at room temperature and at 55 C. It was observed that the morphological evolution of polyethylene is affected by the existence of clay platelets as well as the deformation temperature and strain rate. Martensitic transformation of orthorhombic into monoclinic crystal phases was observed under strain in HDPE, which is delayed and hindered in the presence of clay nanoplatelets. From the SAXS measurements, it was observed that the thickness of the interlamellar amorphous region increased with increasing strain, which is due to elongation of the amorphous chains. The increase in amorphous layer thickness is slightly higher for the nanocomposites compared to the neat polymer.

  10. 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

  11. Pinhole-type two-dimensional ultra-small-angle X-ray scattering on the micrometer scale.

    PubMed

    Kishimoto, Hiroyuki; Shinohara, Yuya; Suzuki, Yoshio; Takeuchi, Akihisa; Yagi, Naoto; Amemiya, Yoshiyuki

    2014-01-01

    A pinhole-type two-dimensional ultra-small-angle X-ray scattering set-up at a so-called medium-length beamline at SPring-8 is reported. A long sample-to-detector distance, 160.5 m, can be used at this beamline and a small-angle resolution of 0.25 µm(-1) was thereby achieved at an X-ray energy of 8 keV. PMID:24365910

  12. Pinhole-type two-dimensional ultra-small-angle X-ray scattering on the micrometer scale

    PubMed Central

    Kishimoto, Hiroyuki; Shinohara, Yuya; Suzuki, Yoshio; Takeuchi, Akihisa; Yagi, Naoto; Amemiya, Yoshiyuki

    2014-01-01

    A pinhole-type two-dimensional ultra-small-angle X-ray scattering set-up at a so-called medium-length beamline at SPring-8 is reported. A long sample-to-detector distance, 160.5 m, can be used at this beamline and a small-angle resolution of 0.25 µm−1 was thereby achieved at an X-ray energy of 8 keV. PMID:24365910

  13. High-speed reference-beam-angle control technique for holographic memory drive

    NASA Astrophysics Data System (ADS)

    Yamada, Ken-ichiro; Ogata, Takeshi; Hosaka, Makoto; Fujita, Koji; Okuyama, Atsushi

    2016-09-01

    We developed a holographic memory drive for next-generation optical memory. In this study, we present the key technology for achieving a high-speed transfer rate for reproduction, that is, a high-speed control technique for the reference beam angle. In reproduction in a holographic memory drive, there is the issue that the optimum reference beam angle during reproduction varies owing to distortion of the medium. The distortion is caused by, for example, temperature variation, beam irradiation, and moisture absorption. Therefore, a reference-beam-angle control technique to position the reference beam at the optimum angle is crucial. We developed a new optical system that generates an angle-error-signal to detect the optimum reference beam angle. To achieve the high-speed control technique using the new optical system, we developed a new control technique called adaptive final-state control (AFSC) that adds a second control input to the first one derived from conventional final-state control (FSC) at the time of angle-error-signal detection. We established an actual experimental system employing AFSC to achieve moving control between each page (Page Seek) within 300 µs. In sequential multiple Page Seeks, we were able to realize positioning to the optimum angles of the reference beam that maximize the diffracted beam intensity. We expect that applying the new control technique to the holographic memory drive will enable a giga-bit/s-class transfer rate.

  14. Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique

    SciTech Connect

    Al Azzawe, A. J. M.

    2007-02-14

    Inelastic scattering is an essential reaction for other nuclear reactions to detect the optical model and compound nucleus formation within the range of (0.4- 5.0) MeV neutron incident energy by using time of flight technique. The time of flight system (TOFS) installed on the horizontal channel reactor RRA has been used to measure the asymmetry of scattered fast neutrons, when data acquisition and system control were recorded event by event by HP - computer via CAMAC system. Eight NE 213 neutron counters were used in order to detect neutron inelastic scattering in the forward direction (4 neutron counters at 0 deg. angle) and in the backward direction (4 neutron counters at 180 deg. angle) to measure the asymmetry of fast neutron. Each neutron counter was 50cm in length and 8cm in diameter, viewed by two (58 - DVP) photomultiplier tubes. The contribution of direct interaction to the compound nucleus formation was deduced from the asymmetry in the neutron detection at the same direction of these eight neutron counters. A time resolution of 8.2 ns between the eight neutron counters and one of the two Ge(Li) detectors has been obtained.

  15. Accelerated wavefront determination technique for optical imaging through scattering medium

    NASA Astrophysics Data System (ADS)

    He, Hexiang; Wong, Kam Sing

    2016-03-01

    Wavefront shaping applied on scattering light is a promising optical imaging method in biological systems. Normally, optimized modulation can be obtained by a Liquid-Crystal Spatial Light Modulator (LC-SLM) and CCD hardware iteration. Here we introduce an improved method for this optimization process. The core of the proposed method is to firstly detect the disturbed wavefront, and then to calculate the modulation phase pattern by computer simulation. In particular, phase retrieval method together with phase conjugation is most effective. In this way, the LC-SLM based system can complete the wavefront optimization and imaging restoration within several seconds which is two orders of magnitude faster than the conventional technique. The experimental results show good imaging quality and may contribute to real time imaging recovery in scattering medium.

  16. An ultra-high vacuum chamber for scattering experiments featuring in-vacuum continuous in-plane variation of the angle between entrance and exit vacuum ports

    SciTech Connect

    Englund, Carl-Johan; Agåker, Marcus Fredriksson, Pierre; Olsson, Anders; Johansson, Niklas; Rubensson, Jan-Erik; Nordgren, Joseph

    2015-09-15

    A concept that enables in-vacuum continuous variation of the angle between two ports in one plane has been developed and implemented. The vacuum chamber allows for measuring scattering cross sections as a function of scattering angle and is intended for resonant inelastic X-ray scattering experiments. The angle between the ports can be varied in the range of 30°-150°, while the pressure change is less than 2 × 10{sup −10} mbars.

  17. 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.; Littrell, Ken C.; Cheng, Yongqiang Q.; Wildgruber, Christoph U.; Jones, Lacy L.; Ramirez-Cuesta, Anibal J.; Rother, Gernot; Dudney, Nancy J.

    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.

  18. Small-angle neutron scattering studies of the template-mediated crystallization of ZSM-5 type zeolite

    SciTech Connect

    Iton, L.E.; Brun, T.O.; Epperson, J.E. . Materials Science and Technology Div.); Trouw, F. . Intense Pulsed Neutron Source Program); White, J.W.; Henderson, S.J. )

    1988-03-01

    Small-angle neutron scattering is a useful new approach to the study of zeolite crystallization from aluminosilicate gels and the action of template molecules. It has been applied to gels for synthesis of zeolite ZSM-5 using tetrapropylammonium ions as templates where the scattering length densities of the gel particles and their texture were determined using contrast variation methods. Gels formulated from soluble silicate incorporate template molecules promptly into an amorphous embryonic'' structure and crystallization ensues via a solid hydrogel transformation mechanism. Gels formulated from colloidal silica show different scattering behavior, and a liquid phase transport mechanism is inferred. 8 refs., 4 figs., 2 tabs.

  19. A recoil detector for the measurement of antiproton-proton elastic scattering at angles close to 90°

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Bechstedt, U.; Gillitzer, A.; Grzonka, D.; Khoukaz, A.; Klehr, F.; Lehrach, A.; Prasuhn, D.; Ritman, J.; Sefzick, T.; Stockmanns, T.; Täschner, A.; Wuestner, P.; Xu, H.

    2014-10-01

    The design and construction of a recoil detector for the measurement of recoil protons of antiproton-proton elastic scattering at scattering angles close to are described. The performance of the recoil detector has been tested in the laboratory with radioactive sources and at COSY with proton beams by measuring proton-proton elastic scattering. The results of laboratory tests and commissioning with beam are presented. Excellent energy resolution and proper working performance of the recoil detector validate the conceptual design of the KOALA experiment at HESR to provide the cross section data needed to achieve a precise luminosity determination at the PANDA experiment.

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

    SciTech Connect

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

    2005-11-01

    We study dilute aqueous solutions of charged disklike mineral particles (laponite) by a combination of static light scattering (SLS) and small-angle x-ray scattering (SAXS). Laponite solutions are known to form gels above a certain critical concentration that must be described as nonequilibrium states. Here we focus on the investigation by SLS and SAXS at concentrations below gelation (c<0.016 g/L) and at low concentrations of added salt (0.001M and 0.005M). Thus, we have obtained the scattering function of single Laponite platelets as well as the structure factor describing their interaction at finite concentration. A detailed analysis of the combined sets of data proves that the solutions are in a well-defined equilibrium state. Moreover, this analysis demonstrates the internal consistency and accuracy of the scattering functions obtained at finite concentrations. We find that laponite particles interact through an effective pair potential that is attractive on short range but repulsive on longer range. This finding demonstrates that Laponite solutions exhibit only a limited stability at the concentration of added salt used herein. Raising the ionic strength to 0.005M already leads to slow flocculation as is evidenced from the enhanced scattering intensity at smallest scattering angles. All data strongly suggest that the gelation occurring at higher concentration is related to aggregation.

  1. Determination by Small-angle X-ray Scattering of Pore Size Distribution in Nanoporous Track-etched Polycarbonate Membranes

    NASA Astrophysics Data System (ADS)

    Jonas, A. M.; Legras, R.; Ferain, E.

    1998-03-01

    Nanoporous track-etched membranes with narrow pore size distributions and average pore size diameters tunable from 100 to 1000 Åare produced by the chemical etching of latent tracks in polymer films after irradiation by a beam of accelerated heavy ions. Nanoporous membranes are used for highly demanding filtration purposes, or as templates to obtain metallic or polymeric nanowires (L. Piraux et al., Nucl. Instr. Meth. Phys. Res. 1997, B131, 357). Such applications call for developments in nanopore size characterization techniques. In this respect, we report on the characterization by small-angle X-ray scattering (SAXS) of nanopore size distribution (nPSD) in polycarbonate track-etched membranes. The obtention of nPSD requires inverting an ill-conditioned inhomogeneous equation. We present different numerical routes to overcome the amplification of experimental errors in the resulting solutions, including a regularization technique allowing to obtain the nPSD without a priori knowledge of its shape. The effect of deviations from cylindrical pore shape on the resulting distributions are analyzed. Finally, SAXS results are compared to results obtained by electron microscopy and conductometry.

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

    PubMed

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

    2014-11-01

    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.

  3. Probing kinetics and dynamics of nanocomposites with grazing-incidence small-angle x-ray scattering.

    NASA Astrophysics Data System (ADS)

    Wang, Jin

    2009-03-01

    Synthesizing complex nanocomposites and superstructures is of great interest in all areas of materials science and involving biology, chemistry, physics and engineering applications such as the fabrication of novel electronic, magnetic, and photonic devices. Since the entire synthesis and assembly process can take place far from equilibrium conditions, a controlled process has to be guided by a thorough understanding of the kinetics and dynamics in the composites. This requires measurement of the structure in situ and in real time with subnanometer spatial resolution and millisecond to subsecond temporal resolution. As an increasingly important structural-characterization technique, grazing-incidence small-angle x-ray scattering (GISAXS) finds vast applications in the research of nanostructures and nanocomposites at surfaces and interfaces. Most significantly, as a complementary method to conventional surface-sensitive tools such as scanning probe microscopy and electron microscopy, GISAXS can be used in situ and in real time to monitor the formation of the nanostructure or nanocomposite, which makes it most suitable for studying the kinetics of nanoassembly processes. The GISAXS technique can also be an integral part of numerous research, for example, those involving kinetics of mesoscaled ordered block copolymer thin films, kinetics of sol-gel processes, quantum dots, nanoparticles in ultrathin films, and dynamics and phase transitions 2D nanocrystal superlattices. Here, I will focus on the applications of GISAXS in real-time structure characterization, the dynamics in polymer/nanoparticle nanocomposies, and the challenges to elucidate nanostructure formation in nanoscience and nanotechnology.

  4. Structural characterization of the human cerebral myelin sheath by small angle x-ray scattering.

    PubMed

    De Felici, M; Felici, R; Ferrero, C; Tartari, A; Gambaccini, M; Finet, S

    2008-10-21

    Myelin is a multi-lamellar membrane surrounding neuronal axons and increasing their conduction velocity. When investigated by small-angle x-ray scattering (SAXS), the lamellar quasi-periodical arrangement of the myelin sheath gives rise to distinct peaks, which allow the determination of its molecular organization and the dimensions of its substructures. In this study we report on the myelin sheath structural determination carried out on a set of human brain tissue samples coming from surgical biopsies of two patients: a man around 60 and a woman nearly 90 years old. The samples were extracted either from white or grey cerebral matter and did not undergo any manipulation or chemical-physical treatment, which could possibly have altered their structure, except dipping them into a formalin solution for their conservation. Analysis of the scattered intensity from white matter of intact human cerebral tissue allowed the evaluation not only of the myelin sheath periodicity but also of its electronic charge density profile. In particular, the thicknesses of the cytoplasm and extracellular regions were established, as well as those of the hydrophilic polar heads and hydrophobic tails of the lipid bilayer. SAXS patterns were measured at several locations on each sample in order to establish the statistical variations of the structural parameters within a single sample and among different samples. This work demonstrates that a detailed structural analysis of the myelin sheath can also be carried out in randomly oriented samples of intact human white matter, which is of importance for studying the aetiology and evolution of the central nervous system pathologies inducing myelin degeneration. PMID:18812651

  5. Structural characterization of the human cerebral myelin sheath by small angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    DeFelici, M.; Felici, R.; Ferrero, C.; Tartari, A.; Gambaccini, M.; Finet, S.

    2008-10-01

    Myelin is a multi-lamellar membrane surrounding neuronal axons and increasing their conduction velocity. When investigated by small-angle x-ray scattering (SAXS), the lamellar quasi-periodical arrangement of the myelin sheath gives rise to distinct peaks, which allow the determination of its molecular organization and the dimensions of its substructures. In this study we report on the myelin sheath structural determination carried out on a set of human brain tissue samples coming from surgical biopsies of two patients: a man around 60 and a woman nearly 90 years old. The samples were extracted either from white or grey cerebral matter and did not undergo any manipulation or chemical-physical treatment, which could possibly have altered their structure, except dipping them into a formalin solution for their conservation. Analysis of the scattered intensity from white matter of intact human cerebral tissue allowed the evaluation not only of the myelin sheath periodicity but also of its electronic charge density profile. In particular, the thicknesses of the cytoplasm and extracellular regions were established, as well as those of the hydrophilic polar heads and hydrophobic tails of the lipid bilayer. SAXS patterns were measured at several locations on each sample in order to establish the statistical variations of the structural parameters within a single sample and among different samples. This work demonstrates that a detailed structural analysis of the myelin sheath can also be carried out in randomly oriented samples of intact human white matter, which is of importance for studying the aetiology and evolution of the central nervous system pathologies inducing myelin degeneration.

  6. Validating Solution Ensembles from Molecular Dynamics Simulation by Wide-Angle X-ray Scattering Data

    PubMed Central

    Chen, Po-chia; Hub, Jochen S.

    2014-01-01

    Wide-angle x-ray scattering (WAXS) experiments of biomolecules in solution have become increasingly popular because of technical advances in light sources and detectors. However, the structural interpretation of WAXS profiles is problematic, partly because accurate calculations of WAXS profiles from structural models have remained challenging. In this work, we present the calculation of WAXS profiles from explicit-solvent molecular dynamics (MD) simulations of five different proteins. Using only a single fitting parameter that accounts for experimental uncertainties because of the buffer subtraction and dark currents, we find excellent agreement to experimental profiles both at small and wide angles. Because explicit solvation eliminates free parameters associated with the solvation layer or the excluded solvent, which would require fitting to experimental data, we minimize the risk of overfitting. We further find that the influence from water models and protein force fields on calculated profiles are insignificant up to q≈15nm−1. Using a series of simulations that allow increasing flexibility of the proteins, we show that incorporating thermal fluctuations into the calculations significantly improves agreement with experimental data, demonstrating the importance of protein dynamics in the interpretation of WAXS profiles. In addition, free MD simulations up to one microsecond suggest that the calculated profiles are highly sensitive with respect to minor conformational rearrangements of proteins, such as an increased flexibility of a loop or an increase of the radius of gyration by < 1%. The present study suggests that quantitative comparison between MD simulations and experimental WAXS profiles emerges as an accurate tool to validate solution ensembles of biomolecules. PMID:25028885

  7. Studies of Particle Sedimentation by Novel Scattering Techniques

    NASA Technical Reports Server (NTRS)

    Tong, Penger

    2000-01-01

    The four-year grant began May 1, 1996 (5-1-96 to 4-30-00, $100,000/year). We have finished 4 major research projects and published 10 papers during this grant period. An important aspect of this research has been the education of students at graduate and undergraduate levels. They have been fully involved in the research described below: 1. Polymer-induced depletion interaction in colloid-polymer mixtures. 2. Colloidal sedimentation in polymer solutions. 3. Velocity fluctuations in particle sedimentation. New laser light scattering techniques for velocity difference measurements.

  8. Efficient Computational Techniques for Electromagnetic Propagation and Scattering.

    NASA Astrophysics Data System (ADS)

    Wagner, Robert Louis

    Electromagnetic propagation and scattering problems are important in many application areas such as communications, high-speed circuitry, medical imaging, geophysical remote sensing, nondestructive testing, and radar. This thesis develops several new techniques for the efficient computer solution of such problems. Most of this thesis deals with the efficient solution of electromagnetic scattering problems formulated as surface integral equations. A standard method of moments (MOM) formulation is used to reduce the problem to the solution of a dense, N times N matrix equation, where N is the number of surface current unknowns. An iterative solution technique is used, requiring the computation of many matrix-vector multiplications. Techniques developed for this problem include the ray-propagation fast multipole algorithm (RPFMA), which is a simple, non-nested, physically intuitive technique based on the fast multipole method (FMM). The RPFMA is implemented for two-dimensional surface integral equations, and reduces the cost of a matrix-vector multiplication from O(N^2) to O(N^ {4/3}). The use of wavelets is also studied for the solution of two-dimensional surface integral equations. It is shown that the use of wavelets as basis functions produces a MOM matrix with substantial sparsity. However, unlike the RPFMA, the use of a wavelet basis does not reduce the computational complexity of the problem. In other words, the sparse MOM matrix in the wavelet basis still has O(N ^2) significant entries. The fast multipole method-fast Fourier transform (FMM-FFT) method is developed to compute the scattering of an electromagnetic wave from a two-dimensional rough surface. The resulting algorithm computes a matrix-vector multiply in O(N log N) operations. This algorithm is shown to be more efficient than another O(N log N) algorithm, the multi-level fast multipole algorithm (MLFMA), for surfaces of small height. For surfaces with larger roughness, the MLFMA is found to be more

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

    SciTech Connect

    Chen, Lingling

    1996-04-01

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

  10. A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence

    NASA Astrophysics Data System (ADS)

    Huber, Franz J. T.; Altenhoff, Michael; Will, Stefan

    2016-05-01

    A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiation signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples.

  11. A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence.

    PubMed

    Huber, Franz J T; Altenhoff, Michael; Will, Stefan

    2016-05-01

    A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiation signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples. PMID:27250387

  12. From nuclei to micro-structure in colloidal crystallization: Investigating intermediate length scales by small angle laser light scattering

    NASA Astrophysics Data System (ADS)

    Beyer, Richard; Franke, Markus; Schöpe, Hans Joachim; Bartsch, Eckhard; Palberg, Thomas

    2015-08-01

    Hard sphere suspensions are well recognized model systems of statistical physics and soft condensed matter. We here investigate the temporal evolution of the immediate environment of nucleating and growing crystals and/or their global scale distribution using time resolved Small Angle Light Scattering (SALS). Simultaneously performed Bragg scattering measurements provide an accurate temporal gauging of the sequence of events. We apply this approach to studies of re-crystallization in several different shear molten hard sphere and attractive hard sphere samples with the focus being on the diversity of observable signal shapes and their change in time. We demonstrate that depending on the preparation conditions different processes occur on length scales larger than the structural scale, which significantly influence both the crystallization kinetics and the final micro-structure. By careful analysis of the SALS signal evolution and by comparing different suggestions for small angle signal shapes to our data, we can for most cases identify the processes leading to the observed signals. These include form factor scattering from crystals surrounded by depletion zones and structure factor scattering from late stage inter-crystallite ordering. The large variety of different small angle signals thus in principle contains valuable information complementary to that gained from Bragg scattering or microscopy. Our comparison, however, also shows that further refinement and adaptation of the theoretical expressions to the sample specific boundary conditions is desired for a quantitative kinetic analysis of micro-structural evolution.

  13. Method for direct detection of pitch angle scattering of energetic electrons caused by whistler mode chorus emissions

    NASA Astrophysics Data System (ADS)

    Kitahara, M.; Katoh, Y.

    2016-06-01

    The Wave-Particle Interaction Analyzer (WPIA), a new instrument proposed by Fukuhara et al. (2009), measures the relative phase angle between the wave magnetic field vector and the velocity vector of each particle and calculates the energy exchange from waves to particles. In this study, we expand its applicability by proposing a method of using the WPIA to directly detect pitch angle scattering of resonant particles by plasma waves by calculating the g values. The g value is defined as the accumulation value of the Lorentz force acting on each particle and indicates the lost momentum of waves. We apply the proposed method to the results of a one-dimensional electron hybrid simulation reproducing the generation of whistler mode chorus emissions around the magnetic equator. Using the wave and particle data obtained at fixed observation points assumed in the simulation system, we conduct a pseudo-observation of the simulation result using the WPIA and analyze the g values. Our analysis yielded significant values indicating the strong pitch angle scattering for electrons in the kinetic energy and pitch angle ranges satisfying the cyclotron resonance condition with the reproduced chorus emissions. The results of this study demonstrate that the proposed method enables us to directly and quantitatively identify the location at which pitch angle scattering occurs in the simulation system and that the method can be applied to the results of space-based observations by the forthcoming Exploration of energization and Radiation in Geospace (ERG) satellite.

  14. Development of a One-Dimensional Small-Angle Neutron Scattering Instrument at the University of Illinois TRIGA Reactor Laboratory

    NASA Astrophysics Data System (ADS)

    Monti, D. A.; Guillermo, N. R.; Hulin, M. J.; Heuser, B. J.; Toreja, A.; Moschetti, T. L.

    1996-03-01

    A small-angle neutron scattering instrument with slit-smeared geometry (1-D SANS) has been constructed at the University of Illinois 1.5 MWatt TRIGA reactor. This facility falls under the general heading of "low-flux research reactors" which typically are not used for neutron scattering research. Low-flux reactors can support neutron scattering research under certain conditions, however. 1-D SANS using elastically-bent crystal optics is one such example [Popovici, et al. (1995). J. Phys. Chem. Solids 56, 1425-1431]. Our instrument uses a pyrolytic graphite pre-monochromator and two elastically-bent Si wafers, all in a (+,+,-) configuration. Instrumental performance including low-angle resolution, on-sample intensity, resolution variability, and cross-section measurement capability will be presented.

  15. 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.

  16. Nanostructural features in silica-polyvinyl acetate nanocomposites characterized by small-angle scattering.

    SciTech Connect

    Narayanan, R. A.; Thiyagarajan, P.; Zhu, A. J.; Ash, J.; Shofner, M. L.; Schadler, L. S.; Kumar, S. K.; Sternstein, S. S.; ORNL; Rensselaer Polytechnic Inst.

    2007-09-10

    Small-angle scattering (SAS) experiments were carried out on nanocomposites of poly(vinyl acetate) (PVAc) and fumed silica nanoparticles with different surface areas and chemical treatment, in the wave-vector (Q) range: 0.0002-1 Angstrom{sup -1}. SAS data on composites with matrices of two different molecular weights indicate that the particle aggregation is independent of the molecular weight of the matrix for a fixed filler concentration and surface treatment. Particle size distributions derived from the SAS data suggest that particle aggregation is reduced when the native surface hydroxyl groups are blocked by various surface treatments, which also reduce the bonding strength to the polymer matrix. The unified exponential/power-law analysis of the SAS data shows three levels of hierarchy in the organization of silica particles. The first level consists of small aggregates of silica particles. At the second level we observe polydispersed aggregates resembling mass-fractal objects that is corroborated by TEM. The polydispersed aggregates further associate to form agglomerates at the third level. The relevance of these findings to the mechanism of nanofiller reinforcement of linear amorphous polymers above T{sub g} is discussed.

  17. 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.

  18. Nanostructural Features in Silica-polyvinyl Acetate Nanocomposites Characterized by Small-Angle Scattering

    SciTech Connect

    Raghavan, Aravinda N; Thiyagarajan, P.; Zhu, Dr. Ai-Jun; Ash, Dr. Benjamin J.; Shofner, M. L.; Schadler, Linda; Kumar, Sanat K; Sternstein, S. S.

    2007-01-01

    Small-angle scattering (SAS) experiments were carried out on nanocomposites of poly(vinyl acetate) (PVAc) and fumed silica nanoparticles with different surface areas and chemical treatment, in the wave-vector (Q) range: 0.0002-1 A-1 . SAS data on composites with matrices of two different molecular weights indicate that the particle aggregation is independent of the molecular weight of the matrix for a fixed filler concentration and surface treatment. Particle size distributions derived from the SAS data suggest that particle aggregation is reduced when the native surface hydroxyl groups are blocked by various surface treatments, which also reduce the bonding strength to the polymer matrix. The unified exponential/power-law analysis of the SAS data shows three levels of hierarchy in the organization of silica particles. The first level consists of small aggregates of silica particles. At the second level we observe polydispersed aggregates resembling mass-fractal objects that is corroborated by TEM. The polydispersed aggregates further associate to form agglomerates at the third level. The relevance of these findings to the mechanism of nanofiller reinforcement of linear amorphous polymers above Tg is discussed.

  19. 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.

  20. Collagen Orientation and Crystallite Size in Human Dentin: A Small Angle X-ray Scattering Study

    SciTech Connect

    Pople, John A.

    2001-03-29

    The mechanical properties of dentin are largely determined by the intertubular dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. The authors perform a small angle x-ray scattering (SAXS) study on fully mineralized human dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the dentino-enamel junction. The thickness of these crystallites, {approx} 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of dentinogenesis and maturation.

  1. A semi-numerical model for near-critical angle scattering.

    PubMed

    Fradkin, Larissa Ju; Darmon, Michel; Chatillon, Sylvain; Calmon, Pierre

    2016-01-01

    Numerous phenomena in the fields of physics and mathematics as seemingly different as seismology, ultrasonics, crystallography, photonics, relativistic quantum mechanics, and analytical number theory are described by integrals with oscillating integrands that contain three coalescing criticalities, a branch point, stationary phase point, and pole as well as accumulation points at which the speed of integrand oscillation is infinite. Evaluating such integrals is a challenge addressed in this paper. A fast and efficient numerical scheme based on the regularized composite Simpson's rule is proposed, and its efficacy is demonstrated by revisiting the scattering of an elastic plane wave by a stress-free half-plane crack embedded in an isotropic and homogeneous solid. In this canonical problem, the head wave, edge diffracted wave, and reflected (or compensating) wave each can be viewed as a respective contribution of a branch point, stationary phase point, and pole. The proposed scheme allows for a description of the non-classical diffraction effects near the "critical" rays (rays that separate regions irradiated by the head waves from their respective shadow zones). The effects include the spikes present in diffraction coefficients at the critical angles in the far field as well as related interference ripples in the near field. PMID:26827012

  2. Interactive graphical system for small-angle scattering analysis of polydisperse systems

    NASA Astrophysics Data System (ADS)

    Konarev, P. V.; Volkov, V. V.; Svergun, D. I.

    2016-09-01

    A program suite for one-dimensional small-angle scattering analysis of polydisperse systems and multiple data sets is presented. The main program, POLYSAS, has a menu-driven graphical user interface calling computational modules from ATSAS package to perform data treatment and analysis. The graphical menu interface allows one to process multiple (time, concentration or temperature-dependent) data sets and interactively change the parameters for the data modelling using sliders. The graphical representation of the data is done via the Winteracter-based program SASPLOT. The package is designed for the analysis of polydisperse systems and mixtures, and permits one to obtain size distributions and evaluate the volume fractions of the components using linear and non-linear fitting algorithms as well as model-independent singular value decomposition. The use of the POLYSAS package is illustrated by the recent examples of its application to study concentration-dependent oligomeric states of proteins and time kinetics of polymer micelles for anticancer drug delivery.

  3. 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.

  4. Using Small-Angle Neutron Scattering to Detect Nanoscopic Lipid Domains

    SciTech Connect

    Pan, Jianjun; Heberle, Frederick A; Petruzielo, Robin S; Katsaras, John

    2013-01-01

    The cell plasma membrane is a complex system, which is thought to be capable of exhibiting non-random lateral organization. Studies of live cells and model membranes have yielded mechanisms responsible for the formation, growth, and maintenance of nanoscopic heterogeneities, although the existence and mechanisms that give rise to these heterogeneities remain controversial. Small-angle neutron scattering (SANS) is a tool ideally suited to interrogate lateral heterogeneity in model membranes, primarily due to its unique spatial resolution (i.e., "5 100 nm) and its ability to resolve structure with minimal perturbation to the membrane. In this review we examine several methods used to analyze the SANS signal arising from freely suspended unilamellar vesicles containing lateral heterogeneity. Specifically, we discuss an analytical model for a single, round domain on a spherical vesicle. We then discuss a numerical method that uses Monte Carlo simulation to describe systems with multiple domains and/or more complicated morphologies. Also discussed are several model-independent approaches that are sensitive to membrane heterogeneity. The review concludes with several recent applications of SANS to the study of membrane raft mixtures.

  5. Small angle neutron scattering contrast variation reveals heterogeneities of interactions in protein gels.

    PubMed

    Banc, A; Charbonneau, C; Dahesh, M; Appavou, M-S; Fu, Z; Morel, M-H; Ramos, L

    2016-06-28

    We propose a quantitative approach to probe the spatial heterogeneities of interactions in macromolecular gels, based on a combination of small angle X-ray (SAXS) and neutrons (SANS) scattering. We investigate the structure of model gluten protein gels and show that the gels display radically different SAXS and SANS profiles when the solvent is (at least partially) deuterated. The detailed analysis of the SANS signal as a function of the solvent deuteration demonstrates heterogeneities of sample deuteration at different length scales. The progressive exchange between the protons (H) of the proteins and the deuteriums (D) of the solvent is inhomogeneous and 60 nm large zones that are enriched in H are evidenced. In addition, at low protein concentration, in the sol state, solvent deuteration induces a liquid/liquid phase separation. Complementary biochemical and structure analyses show that the denser protein phase is more protonated and specifically enriched in glutenin, the polymeric fraction of gluten proteins. These findings suggest that the presence of H-rich zones in gluten gels would arise from the preferential interaction of glutenin polymers through a tight network of non-exchangeable intermolecular hydrogen bonds. PMID:27198847

  6. Small angle neutron scattering (SANS) study of γ' precipitates in single crystals of AM1 superalloy

    NASA Astrophysics Data System (ADS)

    Bellet, D.; Bastie, P.; Royer, A.; Lajzerowicz, J.; Legrand, J. F.; Bonnet, R.

    1992-06-01

    The morphology of γ' precipitates of AM1 single crystal superalloys has been studied by small neutron scattering (SANS), and electron microscopy. Due to the single crystal nature of the samples, the SANS patterns are anisotropic and exhibit a fourfold symmetry corresponding both to the shape and to the spatial arrangement of the precipitates in a (001) plane. Measurements for other sample orientations have allowed us to improve the analysis of the shape of the precipitates. After creep deformation along the < 001 > axis, a twofold symmetry corresponding to the “rafting” of the γ' precipitates is observed in the (010) plane. The main effect of heat treatments at 1 050 °C, commonly used for industrial applications, is the coarsening of the precipitates. From the displacement of the correlation peaks towards smaller angles, we deduce an average centre-to-centre spacing between the precipitates which increases with the annealing time from 0.3 μm to 0.6 μm according to the Lifshitz, Slyosov, Wagner behaviour. The results are compared to electron microscopy measurements, performed on the same samples.

  7. A Small-Angle Scattering Study of the Bulk Structure of a Symmetric Diblock Copolymer System

    NASA Astrophysics Data System (ADS)

    Papadakis, Christine M.; Almdal, Kristoffer; Mortensen, Kell; Posselt, Dorthe

    1997-12-01

    The bulk structure of a homologous series of symmetric polystyrene-polybutadiene (SB) diblock copolymers is investigated using small-angle X-ray and neutron scattering (SANS). The study focuses on the lamellar thickness, the lamellar correlation length and the concentration profile as a function of the chain length and the preparation method applied. The characteristic length, D, scales with the chain length, N, in the whole range studied, but with a clear change in scaling exponent near χ N = 29, in accordance with theoretical predictions of a crossover from an Intermediate-Segregation Regime (ISR) to the Strong-Segregation Limit (SSL). In the ISR (χ N simeq 5-29), D is found to scale like D propto N^{0.83} and in the SSL (χ N > 29) like D propto N^{0.61} . The temperature dependence of the SANS spectra is studied for a low molar mass sample in an interval around the order-disorder transition temperature (TODT). The peak position is found to vary more strongly with temperature than expected for Gaussian chains. Only a weak discontinuity of the peak position at TODT is observed. In summary, the phase behavior of symmetric SB diblock copolymers in the bulk spans three regimes: the Gaussian regime in the region χ N < 5, the ISR for 5 < χ N < 29 and the SSL for χ N > 29.

  8. 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.

  9. 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.

  10. 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.

  11. Surface scattering properties estimated from modeling airborne multiple emission angle reflectance data

    NASA Technical Reports Server (NTRS)

    Guinness, Edward A.; Arvidson, Raymond E.; Irons, J. R.; Harding, D. J.

    1991-01-01

    Here, researchers apply the Hapke function to airborne bidirectional reflectance data collected over three terrestrial surfaces. The objectives of the study were to test the range of natural surfaces that the Hapke model fits and to evaluate model parameters in terms of known surface properties. The data used are multispectral and multiple emission angle data collected during the Geologic Remote Sensing Field Experiment (GRSFE) over a mud-cracked playa, an artificially roughened playa, and a basalt cobble strewn playa at Lunar Lake Playa in Nevada. Airborne remote sensing data and associated field measurements were acquired at the same time. The airborne data were acquired by the Advanced Solid State Array Spectroradiometer (ASAS) instrument, a 29-spectral band imaging system. ASAS reflectance data for a cobble-strewn surface and an artificially rough playa surface on Lunar Lake Playa can be explained with the Hanke model. The cobble and rough playa sites are distinguishable by a single scattering albedo, which is controlled by material composition; by the roughness parameter, which appears to be controlled by the surface texture and particle size; and the symmetry factor of the single particle phase function, which is controlled by particle size and shape. A smooth playa surface consisting of compacted, fine-grained particles has reflectance variations that are also distinct from either the cobble site or rough playa site. The smooth playa appears to behave more like a Lambertian surface that cannot be modeled with the Hapke function.

  12. 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.

  13. The accurate assessment of small-angle X-ray scattering data

    DOE PAGES

    Grant, Thomas D.; Luft, Joseph R.; Carter, Lester G.; Matsui, Tsutomu; Weiss, Thomas M.; Martel, Anne; Snell, Edward H.

    2015-01-23

    Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targetsmore » for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality.« less

  14. The accurate assessment of small-angle X-ray scattering data

    SciTech Connect

    Grant, Thomas D.; Luft, Joseph R.; Carter, Lester G.; Matsui, Tsutomu; Weiss, Thomas M.; Martel, Anne; Snell, Edward H.

    2015-01-23

    Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targets for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality.

  15. Kaon Tagging at 0° Scattering Angle for High-Resolution Decay-Pion Spectroscopy

    NASA Astrophysics Data System (ADS)

    Esser, Anselm; Achenbach, Patrick; Arai, Naoki; Ayerbe Gayoso, Carlos; Böhm, Ralph; Borodina, Olga; Bosnar, Damir; Bozkurt, Vakkas; Debenjak, Luka; Distler, Michael O.; Friščić, Ivica; Fujii, Yuu; Gogami, Toshiyuki; Gómez Rodríguez, Mar; Hashimoto, Osamu; Hirose, Satoshi; Kanda, Hiroki; Kaneta, Masashi; Kim, Eunhee; Kusaka, Junichiro; Maeda, Kazushige; Margaryan, Amur; Merkel, Harald; Müller, Ulrich; Nagao, Sho; Nakamura, Satoshi N.; Pochodzalla, Josef; Rappold, Christophe; Reinhold, Joerg; Saito, Takehiko R.; Sanchez Lorente, Alicia; Sánchez Majos, Salvador; Sören Schlimme, Björn; Schoth, Matthias; Schulz, Florian; Sfienti, Concettina; Širca, Simon; Tang, Liguang; Thiel, Michaela; Tsukada, Kyo

    2014-03-01

    At the Mainz Microtron hypernuclei can be studied by (e,e'K) reactions. By detecting the kaon which is emitted in forward direction, with the KAOS spectrometer placed at 0° scattering angle, reactions involving open strangeness production are tagged. High-resolution magnetic spectrometers are then used to coincidentally detect the monoenergetic decay-pions from mesonic two-body weak decays of light hypernuclei at rest. As a pioneering experiment has confirmed, the KAOS spectrometer is exposed to a large flux of background particles, mostly positrons from bremsstrahlung pair production. In order to increase the effciency of kaon identification the KAOS spectrometer was modified to suppress background particles at the cost of a high momentum resolution, which is less important for this experiment. This was achieved by placing up to 14 cm of lead absorbers in front of the detectors, in which positrons are blocked by forming electromagnetic showers while the effect on kaons is limited. An additional time-of-flight wall and a new threshold Čerenkov detector help to increase the detection effciency of kaons.

  16. 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.

  17. Improving small-angle X-ray scattering data for structural analyses of the RNA world

    PubMed Central

    Rambo, Robert P.; Tainer, John A.

    2010-01-01

    Defining the shape, conformation, or assembly state of an RNA in solution often requires multiple investigative tools ranging from nucleotide analog interference mapping to X-ray crystallography. A key addition to this toolbox is small-angle X-ray scattering (SAXS). SAXS provides direct structural information regarding the size, shape, and flexibility of the particle in solution and has proven powerful for analyses of RNA structures with minimal requirements for sample concentration and volumes. In principle, SAXS can provide reliable data on small and large RNA molecules. In practice, SAXS investigations of RNA samples can show inconsistencies that suggest limitations in the SAXS experimental analyses or problems with the samples. Here, we show through investigations on the SAM-I riboswitch, the Group I intron P4-P6 domain, 30S ribosomal subunit from Sulfolobus solfataricus (30S), brome mosaic virus tRNA-like structure (BMV TLS), Thermotoga maritima asd lysine riboswitch, the recombinant tRNAval, and yeast tRNAphe that many problems with SAXS experiments on RNA samples derive from heterogeneity of the folded RNA. Furthermore, we propose and test a general approach to reducing these sample limitations for accurate SAXS analyses of RNA. Together our method and results show that SAXS with synchrotron radiation has great potential to provide accurate RNA shapes, conformations, and assembly states in solution that inform RNA biological functions in fundamental ways. PMID:20106957

  18. Automated acquisition and analysis of small angle X-ray scattering data

    NASA Astrophysics Data System (ADS)

    Franke, Daniel; Kikhney, Alexey G.; Svergun, Dmitri I.

    2012-10-01

    Small Angle X-ray Scattering (SAXS) is a powerful tool in the study of biological macromolecules providing information about the shape, conformation, assembly and folding states in solution. Recent advances in robotic fluid handling make it possible to perform automated high throughput experiments including fast screening of solution conditions, measurement of structural responses to ligand binding, changes in temperature or chemical modifications. Here, an approach to full automation of SAXS data acquisition and data analysis is presented, which advances automated experiments to the level of a routine tool suitable for large scale structural studies. The approach links automated sample loading, primary data reduction and further processing, facilitating queuing of multiple samples for subsequent measurement and analysis and providing means of remote experiment control. The system was implemented and comprehensively tested in user operation at the BioSAXS beamlines X33 and P12 of EMBL at the DORIS and PETRA storage rings of DESY, Hamburg, respectively, but is also easily applicable to other SAXS stations due to its modular design.

  19. In situ small angle neutron scattering revealing ion sorption in microporous carbon electrical double layer capacitors.

    PubMed

    Boukhalfa, Sofiane; Gordon, Daniel; He, Lilin; Melnichenko, Yuri B; Nitta, Naoki; Magasinski, Alexandre; Yushin, Gleb

    2014-03-25

    Experimental studies showed the impact of the electrolyte solvents on both the ion transport and the specific capacitance of microporous carbons. However, the related structure-property relationships remain largely unclear and the reported results are inconsistent. The details of the interactions of the charged carbon pore walls with electrolyte ions and solvent molecules at a subnanometer scale are still largely unknown. Here for the first time we utilize in situ small angle neutron scattering (SANS) to reveal the electroadsorption of organic electrolyte ions in carbon pores of different sizes. A 1 M solution of tetraethylammonium tetrafluoroborate (TEATFB) salt in deuterated acetonitrile (d-AN) was used in an activated carbon with the pore size distribution similar to that of the carbons used in commercial double layer capacitors. In spite of the incomplete wetting of the smallest carbon pores by the d-AN, we observed enhanced ion sorption in subnanometer pores under the applied potential. Such results suggest the visible impact of electrowetting phenomena counterbalancing the high energy of the carbon/electrolyte interface in small pores. This behavior may explain the characteristic butterfly wing shape of the cyclic voltammetry curve that demonstrates higher specific capacitance at higher applied potentials, when the smallest pores become more accessible to electrolyte. Our study outlines a general methodology for studying various organic salts-solvent-carbon combinations.

  20. In situ microfluidic dialysis for biological small-angle X-ray scattering

    PubMed Central

    Skou, Magda; Skou, Søren; Jensen, Thomas G.; Vestergaard, Bente; Gillilan, Richard E.

    2014-01-01

    Owing to the demand for low sample consumption and automated sample changing capabilities at synchrotron small-angle X-ray (solution) scattering (SAXS) beamlines, X-ray microfluidics is receiving continuously increasing attention. Here, a remote-controlled microfluidic device is presented for simultaneous SAXS and ultraviolet absorption measurements during protein dialysis, integrated directly on a SAXS beamline. Microfluidic dialysis can be used for monitoring structural changes in response to buffer exchange or, as demonstrated, protein concentration. By collecting X-ray data during the concentration procedure, the risk of inducing protein aggregation due to excessive concentration and storage is eliminated, resulting in reduced sample consumption and improved data quality. The proof of concept demonstrates the effect of halted or continuous flow in the microfluidic device. No sample aggregation was induced by the concentration process at the levels achieved in these experiments. Simulations of fluid dynamics and transport properties within the device strongly suggest that aggregates, and possibly even higher-order oligomers, are preferentially retained by the device, resulting in incidental sample purification. Hence, this versatile microfluidic device enables investigation of experimentally induced structural changes under dynamically controllable sample conditions. PMID:25242913

  1. 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.

  2. 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.

  3. Small-angle light scattering by airborne particulates: Environnement S.A. continuous particulate monitor

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Thaury, Claire; Mineau, Jean-Luc; Gaubicher, Bertrand

    2010-08-01

    Airborne particulate matter may have an effect on human health. It is therefore necessary to determine and control in real time the evolution of the concentration and mass of particulates in the ambient air. These parameters can be obtained using optical methods. We propose here a new instrument, 'CPM' (continuous particulate monitor), for the measurement of light scattered by ambient particulates at small angles. This geometry allows simultaneous and separate detections of PM10, PM2.5 and PM1 fractions of airborne particulate matter, with no influence of their chemical nature and without using theoretical calculations. The ambient air is collected through a standard sampling head (PM10 inlet according to EN 12341, PM2.5 inlet according to EN 14907; or PM1, TSP inlets, standard US EPA inlets). The analysis of the first measurements demonstrates that this new instrument can detect, for each of the seven defined size ranges, real-time variations of particulate content in the ambient air. The measured concentrations (expressed in number per liter) can be converted into total mass concentrations (expressed in micrograms per cubic meter) of all fractions of airborne particulate matters sampled by the system. Periodic comparison with a beta-attenuation mass monitor (MP101M Beta Gauge Analyzer from Environnement S.A. company) allows the calculation of a calibration factor as a function of the mean particulate density that is used for this conversion. It is then possible to provide real-time relative variations of aerosol mass concentration.

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

    NASA Astrophysics Data System (ADS)

    Howell, Steven C.

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

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

    DOE PAGES

    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 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. Small-angle neutron scattering studies of chlorophyll micelles: Models for bacterial antenna chlorophyll

    PubMed Central

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

    1986-01-01

    Micelles of hydrated chlorophyll a (P740), bacteriochlorophyll a (P865), bacteriochlorophyll c (P750), and pheophytin a prepared in organic media have been studied by small-angle neutron scattering to determine their shape, size, and mass per unit length. All of the micelles are hollow cylinders of well-defined size. The P740 and P750 cylinders are essentially monolayers of macrocycles crosslinked by water, probably in an arrangement similar to that of crystals of chlorophyll derivatives. The P865 micelle is more nearly a bilayer of macrocycles. We show that the curvature necessary to form cylinders probably results from intrinsic curvature of the five-coordinated chlorophyll macrocycle. Studies of P740 micelle formation and the disaggregating effects of another nucleophile (pyridine) are described. As the P750 micelles are nearly identical in size and optical spectra to the rod-shaped structures observed in chlorosomes, and the P865 micelles have optical properties very similar to the in vivo properties of the long-wavelength antenna of purple photosynthetic bacteria, we propose that features of the hydrated cylindrical micelles of these chlorophylls provide good models for antenna chlorophyll in photosynthetic bacteria. Images PMID:16593703

  7. Structure of Nanoporous Biocarbon for Hydrogen Storage as Determined by Small Angle X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Wood, Mikael; Burress, J.; Pobst, J.; Carter, S.; Pfeifer, P.; Wexler, C.; Shah, P.; Suppes, G.

    2008-03-01

    As a member of the Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) our research group studies the properties of nanoporous biocarbon, produced from waste corn cob, with the goal of achieving the Department of Energy's gravimetric and volumetric standards for both hydrogen and methane gas storage. Small Angle X-Ray Scattering (SAXS) is a valuable tool in our investigation of the geometry of the pore space in our carbon samples. In this talk, we will compare the experimental SAXS data with theoretical results for various pore geometries to determine which pore models are consistent with experiment. Using data from nitrogen adsorption isotherms, along with SAXS, yields significant structural information about the pore space. This analysis should allow us to fully optimize our production process and to achieve the DOE's target storage capacities. This work supported by: 1. National Science Foundation (PFI-0438469) 2. U.S. Department of Education (P200A040038) 3. U.S. Department of Energy (DE-AC02-06CH11357) 4. University of Missouri (RB-06-040) 5. U.S. Department of Defense (N00164-07-P-1306) 6. U.S. Department of Energy (DE-FG02-07ER46411)

  8. Static torque-angle relation of human elbow joint estimated with artificial neural network technique.

    PubMed

    Uchiyama, T; Bessho, T; Akazawa, K

    1998-06-01

    Static relations between elbow joint angle and torque at constant muscle activity in normal volunteers were investigated with the aid of an artificial neural network technique. A subject sat on a chair and moved his upper- and forearm in a horizontal plane at the height of his shoulder. The subject was instructed to maintain the elbow joint at a pre-determined angle. The wrist was then pulled to extend the elbow joint by the gravitational force of a weight hanging from a pulley. Integrated electromyograms (IEMGs), elbow and shoulder joint angles and elbow joint torque were measured. Then the relation among IEMGs, joint angles and torque was modeled with the aid of the artificial neural network, where IEMGs and joint angles were the inputs and torque was the output. After back propagation learning, we presented various combinations of IEMGs, shoulder and elbow joint angles to the model and estimated the elbow joint torque to obtain the torque-angle relation for constant muscle activation. The elbow joint torque increased and then decreased with extension of the elbow joint. This suggests that if the forearm is displaced from an equilibrium point, the torque angle relation would not act like a simple spring. In a view of the musculoskeletal structure of the elbow joint, the relation between the elbow joint angle and the moment arm of the elbow flexor muscles seems to have a dominant effect on the torque-angle relation. PMID:9755039

  9. Trends in anomalous small-angle X-ray scattering in grazing incidence for supported nanoalloyed and core-shell metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreazza, P.; Khelfane, H.; Lyon, O.; Andreazza-Vignolle, C.; Ramos, A. Y.; Samah, M.

    2012-06-01

    As atomic structure and morphology of particles are directly correlated to their functional properties, experimental methods probing local and average features of particles at the nanoscale elicit a growing interest. Anomalous small-angle X-ray scattering (ASAXS) is a very attractive technique to investigate the size, shape and spatial distribution of nanoobjects embedded in a homogeneous matrix or in porous media. The anomalous variation of the scattering factor close to an absorption edge enables element specific investigations. In the case of supported nano-objects, the use of grazing incidence is necessary to limit the probed depth. The combination of grazing incidence with the anomalous technique provides a powerful new method, anomalous grazing incidence small-angle X-ray scattering (AGISAXS), to disentangle complex chemical patterns in supported multi-component nano-structures. Nevertheless, a proper data analysis requires accurate quantitative measurements associated to an adapted theoretical framework. This paper presents anomalous methods applied to nanoalloys phase separation in the 1-10 nm size range, and focuses on the application of AGISAXS in bimetallic systems: nanocomposite films and core-shell supported nanoparticles.

  10. Method to study sample object size limit of small-angle x-ray scattering computed tomography

    NASA Astrophysics Data System (ADS)

    Choi, Mina; Ghammraoui, Bahaa; Badal, Andreu; Badano, Aldo

    2016-03-01

    Small-angle x-ray scattering (SAXS) imaging is an emerging medical tool that can be used for in vivo detailed tissue characterization and has the potential to provide added contrast to conventional x-ray projection and CT imaging. We used a publicly available MC-GPU code to simulate x-ray trajectories in a SAXS-CT geometry for a target material embedded in a water background material with varying sample sizes (1, 3, 5, and 10 mm). Our target materials were water solution of gold nanoparticle (GNP) spheres with a radius of 6 nm and a water solution with dissolved serum albumin (BSA) proteins due to their well-characterized scatter profiles at small angles and highly scattering properties. The background material was water. Our objective is to study how the reconstructed scatter profile degrades at larger target imaging depths and increasing sample sizes. We have found that scatter profiles of the GNP in water can still be reconstructed at depths up to 5 mm embedded at the center of a 10 mm sample. Scatter profiles of BSA in water were also reconstructed at depths up to 5 mm in a 10 mm sample but with noticeable signal degradation as compared to the GNP sample. This work presents a method to study the sample size limits for future SAXS-CT imaging systems.

  11. Small-angle and wide-angle X-ray scattering study on the bilayer structure of synthetic and bovine heart cardiolipins

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroshi; Hayakawa, Tomohiro; Ito, Kazuki; Takata, Masaki; Kobayashi, Toshihide

    2010-10-01

    Cardiolipin (CL) is a membrane phospholipid containing four fatty acid chains. CL plays an important role in energy transformation in mitochondria. The disorder of CL biosynthesis is involved in a genetic disease, Barth syndrome. Alteration of fatty acid composition of CLs has been found in Barth syndrome patients, i.e., the decrease of unsaturated fatty acid chains. In this study, we investigated how the degree of saturation alters the structure of CL bilayers by using X-ray scattering. Bovine heart CL and two synthetic CLs were compared. Fatty acid compositions of these three CLs have different saturation. Small-angle X-ray scattering data showed that the decrease of the number of double bonds in the unsaturated fatty acid chains causes to thicken the CL bilayers. In addition, wide-angle X-ray scattering data suggested that the decrease reduces the degree of disorder of the hydrophobic region in a liquid crystalline phase. These results may be related to the dysfunction of mitochondria in Barth syndrome.

  12. Use of dynamic light scattering and small-angle X-ray scattering to characterize new surfactants in solution conditions for membrane-protein crystallization.

    PubMed

    Dahani, Mohamed; Barret, Laurie Anne; Raynal, Simon; Jungas, Colette; Pernot, Pétra; Polidori, Ange; Bonneté, Françoise

    2015-07-01

    The structural and interactive properties of two novel hemifluorinated surfactants, F2H9-β-M and F4H5-β-M, the syntheses of which were based on the structure and hydrophobicity of the well known dodecyl-β-maltoside (DD-β-M), are described. The shape of their micellar assemblies was characterized by small-angle X-ray scattering and their intermicellar interactions in crystallizing conditions were measured by dynamic light scattering. Such information is essential for surfactant phase-diagram determination and membrane-protein crystallization.

  13. The effect of chiropractic techniques on the Cobb angle in idiopathic scoliosis arising in adolescence

    PubMed Central

    Byun, Sunghak; Han, Dongwook

    2016-01-01

    [Purpose] The purpose of this study was to examine whether chiropractic techniques would reduce the curvature of idiopathic scoliosis, which commonly occurs in elementary school children. [Subjects] The subjects of this study were 5 healthy elementary students who listened to an explanation of the study methods and purpose of the study and agreed to participate in the experiment. [Methods] The Cobb angle was measured by taking an X-ray (FCT-1, Dongmun, Goyangsi, Republic of Korea) taken from the rear, using X-ray film. The method of intervention this study used was application of chiropractic techniques. Spinal correction was carried out for 30 minutes per session, which included soft tissue massage, 3 times a week for 8 weeks. [Results] It was established that the Cobb angle was noticeably decreased after 4 weeks of the intervention. Post Hoc analysis revealed that the Cobb angle noticeably decreased after 4 weeks compared with the Cobb angle before the chiropractic techniques were applied. However, no significant difference in Cobb angle was evident after the fourth week. [Conclusion] This study demonstrated that chiropractic techniques can effectively reduce the Cobb angle within as little as 4 weeks. So, we can confirm that the chiropractic techniques were effective for reducing the curvature of idiopathic scoliosis. PMID:27190435

  14. 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.

  15. Anomalous small angle x-ray scattering studies of heavy metal ion solvation behavior in clay minerals

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Winans, R.E.; Song, Kang

    1997-09-01

    The authors have exploited anomalous small angle x-ray scattering (ASAXS) to monitor the solvation behavior of Cu(II), Er(III) and Yb(III) ions within the interlayers of the natural aluminosilicate clay mineral montmorillonite. The ASAXS technique can reveal the distribution of specific metallic species within a heterogeneous and disordered matrix. The variations of signal intensity as a function of absorption energy were monitored for all of the metal-clays as a function of hydration. Two different hydration levels were probed: as prepared at ambient conditions, or so-called {open_quotes}dry{close_quotes} powders, and {open_quotes}wet{close_quotes} pastes. ASAXS intensities should increase with absorption energy if the metal ion is associated with the interlayer solvent (water in this case), and decrease if the metal ion is associated with the solid matrix. The results show that: (1) Cu(II) is solvated within the interlayers of the wet sample, as expected, and (2) Er(III) and Yb(III) decrease in ASAXS intensity with increased hydration. This latter result was not expected and there is speculation that these ions have associated as hydrolyzed products with the clay surface. The basic principles underlying SAXS and ASAXS will also be presented in this paper.

  16. 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.

  17. 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. PMID:16256467

  18. Recent Development of a 36 meter Small-Angle Neutron Scattering BATAN Spectrometer (SMARTer) in Serpong Indonesia

    NASA Astrophysics Data System (ADS)

    Giri Rachman Putra, Edy; Bharoto; Seong, Baek Seok

    2010-10-01

    The 36 meter small-angle neutron scattering (SANS) spectrometer BATAN (SMARTer) in Serpong, Indonesia has been revitalised for several years. The work on replacing, upgrading and improving the control system and the experimental method were conducted in order to setup the spectrometer back in operation. Two main personal computers, one for handling and controlling the mechanical system and another one for acquiring neutron data were employed at the spectrometer. The standard and established SANS data reduction and analysis programs, such as GRASP and NIST Igor have been implemented to subtract the raw scattered neutron data with the backgrounds and then analyse the corrected data. The scattering data of ferrofluids samples, Fe3O4 and MnZnFe2O4 have been obtained using SANS spectrometers in BATAN Serpong, Indonesia and HANARO-KAERI, Republic of Korea for inter-laboratory comparison and investigation of proposed research interest. The results were comparable from both scattering data analysis.

  19. Ultra small angle x-ray scattering in complex mixtures of triacylglycerols

    NASA Astrophysics Data System (ADS)

    Peyronel, Fernanda; Quinn, Bonnie; Marangoni, Alejandro G.; Pink, David A.

    2014-11-01

    Ultra-small angle x-ray scattering (USAXS) has been used to elucidate, in situ, the aggregation structure of unsheared model edible oils. Each system comprised one or two solid lipids and a combination of liquid lipids. The 3D nano- to micro-structures of each system were characterized. The length scale investigated, using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, ANL, ranged from 300 Å-10 µm. Using the Unified Fit model, level-1 analysis showed that the scatterers were 2D objects with either a smooth, a rough, or a diffuse surface. These 2D objects had an average radius of gyration Rg1 between 200-1500 Å. Level-2 analysis displayed a slope between -1 and -2. Use of the Guinier-Porod model gave s ≈ 1 thus showing that it was cylinders (TAGwoods) aggregating with fractal dimension 1 ≤ D2 ≤ 2. D2 = 1 is consistent with 1D structures formed from TAGwoods, while D2 = 2 implies that the TAGwoods had formed structures characteristic of diffusion or reaction limited cluster-cluster aggregation (DLCA/RLCA). These aggregates exhibited radii of gyration, Rg2, between 2500 and 6500 Å. Level-3 analyses showed diffuse surfaces, for most of the systems. These interpretations are in accord with theoretical models which studied crystalline nano-platelets (CNPs) coated with nano-scale layers arising from phase separation at the CNP surfaces. These layers could be due to either liquid-liquid phase separation with the CNPs coated, uniformly or non-uniformly, by a diffuse layer of TAGs, or solid-liquid phase separation with the CNPs coated by a rough layer of crystallites. A fundamental understanding of the self-organizing structures arising in these systems helps advance the characterization of fat crystal networks from nanometres to micrometres. This research can be used to design novel fat structures that use healthier fats via nano- and meso-scale structural engineering.

  20. 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.

  1. Characterization of polybutadiene-poly(ethyleneoxide) aggregates in aqueous solution: A light-scattering and small-angle neutron-scattering study

    SciTech Connect

    Fuetterer, Tobias; Nordskog, Anette; Hellweg, Thomas; Findenegg, Gerhard H.; Foerster, Stephan; Dewhurst, Charles D.

    2004-10-01

    For diblockcopolymers of polybutadiene-poly(ethyleneoxide) (PB-PEO) type, water is a selective solvent. In dependence of the length of both blocks and the block length ratio, these polymers form a multitude of self-assembled structures in solution. In the present work scattering methods are used to investigate the water-soluble polymer PB{sub 125}-PEO{sub 155}. It is found to form long rodlike micelles, which are characterized with respect to the aggregate length L, the cross sectional radius R{sub CS}, the radial scattering length density profile {sigma}(r), and the radial aggregation number N{sub rad}. Model-independent as well as model-based approaches are used for the scattering data analysis. From dynamic light scattering (DLS) and static light scattering (SLS) experiments the weight averaged length L{sub w} of these stiff elongated aggregates is determined to L{sub w}=350 nm. Small angle neutron scattering (SANS) reveals a cross sectional radius of R{sub CS}=17 nm and in combination with results from the SLS the radial aggregation number is found to be N{sub rad}=70.

  2. 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

    2012-10-01

    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.

  3. Metastable ripple phase of fully hydrated dipalmitoylphosphatidylcholine as studied by small angle x-ray scattering

    PubMed Central

    Yao, Haruhiko; Matuoka, Sinzi; Tenchov, Boris; Hatta, Ichiro

    1991-01-01

    Fully hydrated dipalmitoylphosphatidylcholine (DPPC) undergoes liquid crystalline to metastable Pβ, phase transition in cooling. A small angle x-ray scattering study has been performed for obtaining further evidence about the structure of this phase. From a high-resolution observation of x-ray diffraction profiles, a distinct multipeak pattern has become obvious. Among them the (01) reflection in the secondary ripple structure is identified clearly. There are peaks assigned straightforwardly to (10) and (20) reflections in the primary ripple structure and peaks assigned to (10) and (20) reflections in the secondary ripple structure. Therefore the multipeak pattern is due to superposition of the reflections cause by the primary and secondary ripple structures. The lattice parameters are estimated as follows: for the primary ripple structure a = 7.09 nm, b = 13.64 nm, and γ = 95°, and for the secondary ripple structure a = 8.2 nm, b = 26.6 nm, and γ = 90°. The lattice parameters thus obtained for the secondary ripple structure are not conclusive, however. The hydrocarbon chains in the primary ripple structure have been reported as being tilted against the bilayer plane and, on the other hand, the hydrocarbon chains in the secondary ripple structure are likely to be perpendicular to the bilayer plane. This fact seems to be related to a sequential mechanism of phase transitions. On heating from the Lβ, phase where the hydrocarbon chains are tilted the primary ripple structure having tilted hydrocarbon chains takes place and on cooling from the Lα phase where the hydrocarbon chains are not tilted the secondary ripple structure with untilted chains tends to be stabilized. It appears that the truly metastable ripple phase is expressed by the second ripple structure although in the course of the actual cooling transition both the secondary and primary ripple structures form and coexist. PMID:19431787

  4. Simulation Study of the Direct Measurement of the Pitch Angle Scattering of Energetic Electrons by Whistler-Mode Chorus Emissions

    NASA Astrophysics Data System (ADS)

    Kitahara, M.; Katoh, Y.; Kojima, H.; Omura, Y.

    2014-12-01

    Wave-Particle Interaction Analyzer (WPIA), which is a new instrumentation proposed by Fukuhara et al. (2009), measures a relative phase angle between a wave magnetic field vector and a velocity vector of each particle and calculates the energy exchange from waves to particles. The WPIA has a potential to directly detect wave-particle interactions in space plasmas and will be installed on the ERG satellite of JAXA/ISAS. In the present study, in addition to the energy exchange proposed by Fukuhara et al. (2009), we propose the direct measurement of the pitch angle scattering of resonant particles by plasma waves via the WPIA by computing the Lorentz force of wave electromagnetic fields acting on each particle. We apply the proposed method to results of the one-dimensional electron hybrid simulation reproducing the generation of whistler-mode chorus emissions around the magnetic equator [Katoh and Omura, 2007]. By using the wave and particle data obtained at fixed observation points assumed in the simulation system, we analyze the Lorentz force acting on each particle and compute the averaged force in the whole simulation time, corresponding to 20,000 gyro periods. We use 200 keV electrons and the time, kinetic energy, and pitch angle resolutions of 500 gyro-periods, ±10%, and 1 degree, respectively, for the analysis of the averaged Lorentz force. In the result of the analysis, we obtain significant values for electrons in the kinetic energy and pitch angle ranges satisfying the cyclotron resonance condition with the reproduced chorus emissions. The obtained value is three times larger than the magnitude of perturbations in other pitch angle ranges. We compared the result of the analysis with the temporal variation of pitch angle distributions and wave spectra observed at fixed points in the simulation. While the pitch angle distribution varies similarly in both hemispheres, the obtained Lorentz force is only significant in the pitch angle range corresponding to the

  5. Single-crystal CVD diamonds as small-angle X-ray scattering windows for high-pressure research

    PubMed Central

    Wang, Suntao; Meng, Yu-fei; Ando, Nozomi; Tate, Mark; Krasnicki, Szczesny; Yan, Chih-shiue; Liang, Qi; Lai, Joseph; Mao, Ho-kwang; Gruner, Sol M.; Hemley, Russell J.

    2012-01-01

    Small-angle X-ray scattering (SAXS) was performed on single-crystal chemical vapor deposition (CVD) diamonds with low nitrogen concentrations, which were fabricated by microwave plasma-assisted chemical vapor deposition at high growth rates. High optical quality undoped 500 µm-thick single-crystal CVD diamonds grown without intentional nitrogen addition proved to be excellent as windows on SAXS cells, yielding parasitic scattering no more intense than a 7.5 µm-thick Kapton film. A single-crystal CVD diamond window was successfully used in a high-pressure SAXS cell. PMID:22675230

  6. Quaternary structure of alpha-crustacyanin from lobster as seen by small-angle X-ray scattering.

    PubMed

    Dellisanti, Cosma D; Spinelli, Silvia; Cambillau, Christian; Findlay, John B C; Zagalsky, Peter F; Finet, Stéphanie; Receveur-Bréchot, Véronique

    2003-06-01

    The structure of alpha-crustacyanin, the blue carotenoprotein of lobster (Homarus gammarus) carapace, has been investigated for the first time using small-angle X-ray scattering. In this paper, we have determined the dimensions of this protein composed of eight heterodimeric subunits of beta-crustacyanin. Analysis of the scattering spectra and estimation of the shape of alpha-crustacyanin show that the protein fits into a cylinder with an axial length of 238 A and a radius of 47.5 A, in which the eight beta-crustacyanin molecules are probably arranged in a helical manner. PMID:12782314

  7. 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.

  8. Coherent Rayleigh-Brillouin scattering as a flow diagnostic technique

    SciTech Connect

    Graul, J. S.; Lilly, T. C.

    2014-12-09

    Broadband coherent Rayleigh-Brillouin scattering (CRBS) was used to measure translational gas temperatures for nitrogen at the ambient pressure of 0.8 atm using a purpose-built Fabry-Perot etalon spectrometer. Temperatures derived from the CRBS spectral analysis were compared with experimentally-measured temperatures, and were found to be, on average, within 2% of the experimentally-measured value. Axial flow velocities from a double jet at a pressure ratio of 0.38 were also measured by looking at the Doppler shift of the CRBS line shape. With recent developments in chirped laser technology and the capacity of CRBS to simultaneously provide thermodynamic and bulk flow information, the CRBS line shape acquisition and analysis technique presented here may allow for future time-resolved, characterization of aerospace flows.

  9. Note: Comparison of grazing incidence small angle x-ray scattering of a titania sponge structure at the beamlines BW4 (DORIS III) and P03 (PETRA III)

    SciTech Connect

    Rawolle, M.; Koerstgens, V.; Ruderer, M. A.; Metwalli, E.; Guo, S.; Mueller-Buschbaum, P.; Herzog, G.; Benecke, G.; Schwartzkopf, M.; Buffet, A.; Perlich, J.; Roth, S. V.

    2012-10-15

    Grazing incidence small angle x-ray scattering (GISAXS) is a powerful technique for morphology investigation of nanostructured thin films. GISAXS measurements at the newly installed P03 beamline at the storage ring PETRA III in Hamburg, Germany, are compared to the GISAXS data from the beamline BW4 at the storage ring DORIS III, which had been used extensively for GISAXS investigations in the past. As an example, a titania thin film sponge structure is investigated. Compared to BW4, at beamline P03 the resolution of larger structures is slightly improved and a higher incident flux leads to a factor of 750 in scattered intensity. Therefore, the acquisition time in GISAXS geometry is reduced significantly at beamline P03.

  10. Structural evolution of regenerated silk fibroin under shear: Combined wide- and small-angle x-ray scattering experiments using synchrotron radiation

    SciTech Connect

    Rossle, Manfred; Panine, Pierre; Urban, Volker S; Riekel, Christine

    2004-04-01

    The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The aggregates were found to be amorphous with {beta}-conformation according to infrared spectroscopy. Scanning x-ray microdiffraction with a 5 {micro}m beam on aggregated material, which had solidified in air, showed silk II reflections and a material with equatorial reflections close to the silk I structure reflections, but with strong differences in reflection intensities. This silk I type material shows up to two low-angle peaks suggesting the presence of water molecules that might be intercalated between hydrogen-bonded sheets.

  11. Scattering attributes of one-dimensional semiconducting oxide nanomaterials individually probed for varying light-matter interaction angles

    NASA Astrophysics Data System (ADS)

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Hahm, Jong-in

    2015-10-01

    We report the characteristic optical responses of one-dimensional semiconducting oxide nanomaterials by examining the individual nanorods (NRs) of ZnO, SnO2, indium tin oxide, and zinc tin oxide under precisely controlled, light-matter interaction geometry. Scattering signals from a large set of NRs of the different types are evaluated spatially along the NR length while varying the NR tilt angle, incident light polarization, and analyzer rotation. Subsequently, we identify material-indiscriminate, NR tilt angle- and incident polarization-dependent scattering behaviors exhibiting continuous, intermittent, and discrete responses. The insight gained from this study can advance our fundamental understanding of the optical behaviors of the technologically useful nanomaterials and, at the same time, promote the development of highly miniaturized, photonic and bio-optical devices utilizing the spatially controllable, optical responses of the individual semiconducting oxide NRs.

  12. Modulated heterodyne light scattering set-up for measuring long relaxation time at small and wide angle

    SciTech Connect

    Leone, Nancy; Villari, Valentina; Micali, Norberto

    2012-08-15

    We present a simple, compact, and versatile experimental setup working in the heterodyne detection mode with modulation of the reference beam. The system is implemented with a collection optics based on a unimodal optical fiber coupler. This choice allows the heterodyne to be used in a wide range of scattering angles, even for very small ones, without losing the optical beating. The apparatus can be successfully used to study translational diffusive dynamics of dispersed particles at scattering angles smaller than 5 Degree-Sign and it is suitable for exploring slow relaxation processes in sub-Hertz frequency domain, for example, in glass-forming systems. It is also possible to measure the electrophoretic mobility by applying an electric field into a charged particles solution.

  13. Grazing-incidence small-angle X-ray scattering: application to the study of quantum dot lattices

    SciTech Connect

    Buljan, Maja Radić, Nikola; Bernstorff, Sigrid; Dražić, Goran; Bogdanović-Radović, Iva; Holý, Václav

    2012-01-01

    The modelling of grazing-incidence small-angle X-ray scattering (GISAXS) from three-dimensional quantum dot lattices is described. The ordering of quantum dots in three-dimensional quantum dot lattices is investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Theoretical models describing GISAXS intensity distributions for three general classes of lattices of quantum dots are proposed. The classes differ in the type of disorder of the positions of the quantum dots. The models enable full structure determination, including lattice type, lattice parameters, the type and degree of disorder in the quantum dot positions and the distributions of the quantum dot sizes. Applications of the developed models are demonstrated using experimentally measured data from several types of quantum dot lattices formed by a self-assembly process.

  14. Characterizing the Morphologies of Mechanically Manipulated Multiwall Carbon Nanotube Films by Small-Angle X-ray Scattering

    SciTech Connect

    Wang,B.; Bennett, R.; Verploegen, E.; Hart, A.; Cohen, R.

    2007-01-01

    We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological characteristics of pristine and mechanically manipulated multiwall carbon nanotube (MWCNT) films. We determined that CNT diameters measured near the edges of a film were smaller compared to those measured in the interior. Uniaxially compressed MWCNT films exhibited a buckling deformation that was observable both in scanning electron microscopy (SEM) and SAXS. CNT films were also converted into cellular foams of CNTs through capillarity-induced densification. By examining spatially- and time-resolved SAXS data for the cellular foams, we identified low angle features in the scattering curves that correspond to the average spacing between CNTs, demonstrating that SAXS is a useful method for monitoring the packing density of CNTs in a film. For all of the morphologies that were examined (aligned, disordered, compressed, and densified), SAXS data showed good correspondence with SEM images.

  15. Scattering attributes of one-dimensional semiconducting oxide nanomaterials individually probed for varying light-matter interaction angles

    SciTech Connect

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Hahm, Jong-in

    2015-10-12

    We report the characteristic optical responses of one-dimensional semiconducting oxide nanomaterials by examining the individual nanorods (NRs) of ZnO, SnO{sub 2}, indium tin oxide, and zinc tin oxide under precisely controlled, light-matter interaction geometry. Scattering signals from a large set of NRs of the different types are evaluated spatially along the NR length while varying the NR tilt angle, incident light polarization, and analyzer rotation. Subsequently, we identify material-indiscriminate, NR tilt angle- and incident polarization-dependent scattering behaviors exhibiting continuous, intermittent, and discrete responses. The insight gained from this study can advance our fundamental understanding of the optical behaviors of the technologically useful nanomaterials and, at the same time, promote the development of highly miniaturized, photonic and bio-optical devices utilizing the spatially controllable, optical responses of the individual semiconducting oxide NRs.

  16. Performance of the micro-PIC gaseous area detector in small-angle X-ray scattering experiments.

    PubMed

    Hattori, Kaori; Tsuchiya, Ken'ichi; Ito, Kazuki; Okada, Yoko; Fujii, Kotaro; Kubo, Hidetoshi; Miuchi, Kentaro; Takata, Masaki; Tanimori, Toru; Uekusa, Hidehiro

    2009-03-01

    The application of a two-dimensional photon-counting detector based on a micro-pixel gas chamber (micro-PIC) to high-resolution small-angle X-ray scattering (SAXS), and its performance, are reported. The micro-PIC is a micro-pattern gaseous detector fabricated by printed circuit board technology. This article describes the performance of the micro-PIC in SAXS experiments at SPring-8. A dynamic range of >10(5) was obtained for X-ray scattering from a polystyrene sphere solution. A maximum counting rate of up to 5 MHz was observed with good linearity and without saturation. For a diffraction pattern of collagen, weak peaks were observed in the high-angle region in one accumulation of photons.

  17. A study of the effect of formalin preservation on normal and cancerous breast tissues using small angle X-ray scattering (SAXS)

    NASA Astrophysics Data System (ADS)

    Changizi, V.; Wilkinson, S.; Hall, C. J.; Grossmann, G.

    2006-09-01

    Small angle X-ray scattering (SAXS) has the ability to provide information on a molecular and supra-molecular scale from biological tissue specimens. It has been postulated that this information will be useful in providing histopathological diagnoses for certain diseases of the breast. In this category, we include cancer, a major health problem for a number of populations around the world. So far studies in our group have been made using flash-frozen tissue samples. This limits the range and ease of use of the technique. If we were able to obtain the same information from preserved tissues then a more extensive use of SAXS diagnosis would be possible. Here we report on the first investigations into this possibility. In the research reported in this paper, 84 human breast biopsies including cancer and normal tissues were obtained from human patients. Small angle scatter data were collected at station 2.1 of the SRS at the Daresbury Laboratory, UK using a beam size of 0.25 mm 2 at the sample and a wavelength of 1.54 Å. The sample to detector distance was 2000 mm. The results verify that there is a quantifiable difference between the scatter curves from flash-frozen cancer and normal breast tissue in the range of scatter vector Q between 0.4 and 0.7 nm -1. After preserving the tissues in formalin, the difference between the normal and cancerous tissues is less marked. The preservation of the tissue in formalin can essentially mask the effects that disease would have on the tissue supra-molecular structure rendering the preserved specimens of less useful for this histopathology technique.

  18. Relationship Between the Atomic Pair Distribution Function and Small-Angle Scattering: Implications for Modeling of Nanoparticles

    SciTech Connect

    Billinge, S.; Farrowa, C.L.

    2009-05-01

    The relationship between the equations used in the atomic pair distribution function (PDF) method and those commonly used in small-angle-scattering (SAS) analyses is explicitly shown. The origin of the sloping baseline, -4{pi}r{rho}{sub 0}, in PDFs of bulk materials is identified as originating from the SAS intensity that is neglected in PDF measurements. The nonlinear baseline in nanoparticles has the same origin, and contains information about the shape and size of the nanoparticles.

  19. Spectral line polarization with angle-dependent partial frequency redistribution. I. A Stokes parameters decomposition for Rayleigh scattering

    NASA Astrophysics Data System (ADS)

    Frisch, H.

    2010-11-01

    Context. The linear polarization of a strong resonance lines observed near the solar limb is created by a multiple-scattering process. Partial frequency redistribution (PRD) effects must be accounted for to explain the polarization profiles. The redistribution matrix describing the scattering process is a sum of terms, each containing a PRD function multiplied by a Rayleigh type phase matrix. A standard approximation made in calculating the polarization is to average the PRD functions over all the scattering angles, because the numerical work needed to take the angle-dependence of the PRD functions into account is large and not always needed for reasonable evaluations of the polarization. Aims: This paper describes a Stokes parameters decomposition method, that is applicable in plane-parallel cylindrically symmetrical media, which aims at simplifying the numerical work needed to overcome the angle-average approximation. Methods: The decomposition method relies on an azimuthal Fourier expansion of the PRD functions associated to a decomposition of the phase matrices in terms of the Landi Degl'Innocenti irreducible spherical tensors for polarimetry T^K_Q(i, Ω) (i Stokes parameter index, Ω ray direction). The terms that depend on the azimuth of the scattering angle are retained in the phase matrices. Results: It is shown that the Stokes parameters I and Q, which have the same cylindrical symmetry as the medium, can be expressed in terms of four cylindrically symmetrical components I_Q^K (K = Q = 0, K = 2, Q = 0, 1, 2). The components with Q = 1, 2 are created by the angular dependence of the PRD functions. They go to zero at disk center, ensuring that Stokes Q also goes to zero. Each component I_Q^K is a solution to a standard radiative transfer equation. The source term S_Q^K are significantly simpler than the source terms corresponding to I and Q. They satisfy a set of integral equations that can be solved by an accelerated lambda iteration (ALI) method.

  20. 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.

  1. Small angle X-ray scattering and transmission electron microscopy study of the Lactobacillus brevis S-layer protein

    NASA Astrophysics Data System (ADS)

    Jääskeläinen, Pentti; Engelhardt, Peter; Hynönen, Ulla; Torkkeli, Mika; Palva, Airi; Serimaa, Ritva

    2010-10-01

    The structure of self-assembly domain containing recombinant truncation mutants of Lactobacillus brevis surface layer protein SlpA in aqueous solution was studied using small-angle X-ray scattering and transmission electron microscopy. The proteins were found out to interact with each other forming stable globular oligomers of about 10 monomers. The maximum diameter of the oligomers varied between 75 Å and 435 Å.

  2. Accurate small and wide angle x-ray scattering profiles from atomic models of proteins and nucleic acids

    SciTech Connect

    Nguyen, Hung T.; Pabit, Suzette A.; Meisburger, Steve P.; Pollack, Lois; Case, David A.

    2014-12-14

    A new method is introduced to compute X-ray solution scattering profiles from atomic models of macromolecules. The three-dimensional version of the Reference Interaction Site Model (RISM) from liquid-state statistical mechanics is employed to compute the solvent distribution around the solute, including both water and ions. X-ray scattering profiles are computed from this distribution together with the solute geometry. We describe an efficient procedure for performing this calculation employing a Lebedev grid for the angular averaging. The intensity profiles (which involve no adjustable parameters) match experiment and molecular dynamics simulations up to wide angle for two proteins (lysozyme and myoglobin) in water, as well as the small-angle profiles for a dozen biomolecules taken from the BioIsis.net database. The RISM model is especially well-suited for studies of nucleic acids in salt solution. Use of fiber-diffraction models for the structure of duplex DNA in solution yields close agreement with the observed scattering profiles in both the small and wide angle scattering (SAXS and WAXS) regimes. In addition, computed profiles of anomalous SAXS signals (for Rb{sup +} and Sr{sup 2+}) emphasize the ionic contribution to scattering and are in reasonable agreement with experiment. In cases where an absolute calibration of the experimental data at q = 0 is available, one can extract a count of the excess number of waters and ions; computed values depend on the closure that is assumed in the solution of the Ornstein–Zernike equations, with results from the Kovalenko–Hirata closure being closest to experiment for the cases studied here.

  3. Accurate small and wide angle x-ray scattering profiles from atomic models of proteins and nucleic acids.

    PubMed

    Nguyen, Hung T; Pabit, Suzette A; Meisburger, Steve P; Pollack, Lois; Case, David A

    2014-12-14

    A new method is introduced to compute X-ray solution scattering profiles from atomic models of macromolecules. The three-dimensional version of the Reference Interaction Site Model (RISM) from liquid-state statistical mechanics is employed to compute the solvent distribution around the solute, including both water and ions. X-ray scattering profiles are computed from this distribution together with the solute geometry. We describe an efficient procedure for performing this calculation employing a Lebedev grid for the angular averaging. The intensity profiles (which involve no adjustable parameters) match experiment and molecular dynamics simulations up to wide angle for two proteins (lysozyme and myoglobin) in water, as well as the small-angle profiles for a dozen biomolecules taken from the BioIsis.net database. The RISM model is especially well-suited for studies of nucleic acids in salt solution. Use of fiber-diffraction models for the structure of duplex DNA in solution yields close agreement with the observed scattering profiles in both the small and wide angle scattering (SAXS and WAXS) regimes. In addition, computed profiles of anomalous SAXS signals (for Rb(+) and Sr(2+)) emphasize the ionic contribution to scattering and are in reasonable agreement with experiment. In cases where an absolute calibration of the experimental data at q = 0 is available, one can extract a count of the excess number of waters and ions; computed values depend on the closure that is assumed in the solution of the Ornstein-Zernike equations, with results from the Kovalenko-Hirata closure being closest to experiment for the cases studied here.

  4. Accurate small and wide angle x-ray scattering profiles from atomic models of proteins and nucleic acids

    NASA Astrophysics Data System (ADS)

    Nguyen, Hung T.; Pabit, Suzette A.; Meisburger, Steve P.; Pollack, Lois; Case, David A.

    2014-12-01

    A new method is introduced to compute X-ray solution scattering profiles from atomic models of macromolecules. The three-dimensional version of the Reference Interaction Site Model (RISM) from liquid-state statistical mechanics is employed to compute the solvent distribution around the solute, including both water and ions. X-ray scattering profiles are computed from this distribution together with the solute geometry. We describe an efficient procedure for performing this calculation employing a Lebedev grid for the angular averaging. The intensity profiles (which involve no adjustable parameters) match experiment and molecular dynamics simulations up to wide angle for two proteins (lysozyme and myoglobin) in water, as well as the small-angle profiles for a dozen biomolecules taken from the BioIsis.net database. The RISM model is especially well-suited for studies of nucleic acids in salt solution. Use of fiber-diffraction models for the structure of duplex DNA in solution yields close agreement with the observed scattering profiles in both the small and wide angle scattering (SAXS and WAXS) regimes. In addition, computed profiles of anomalous SAXS signals (for Rb+ and Sr2+) emphasize the ionic contribution to scattering and are in reasonable agreement with experiment. In cases where an absolute calibration of the experimental data at q = 0 is available, one can extract a count of the excess number of waters and ions; computed values depend on the closure that is assumed in the solution of the Ornstein-Zernike equations, with results from the Kovalenko-Hirata closure being closest to experiment for the cases studied here.

  5. Measurement of yarn twist based on backward light scattering and small-angle far-field diffraction

    NASA Astrophysics Data System (ADS)

    Pei, Z. G.; Tao, X. M.

    2015-12-01

    This paper presents a non-destructive, non-contact method for measuring the twist of a yarn based on light scattering and diffraction. The surface twist angle is measured by determining the direction of the line with the highest intensity on the backward light scattering pattern which is perpendicular to the surface fibers, which is verified by both theoretical analysis based on Beckmann’s scattering model and experiments. The yarn diameter is measured with good accuracy by using the small-angle far-field diffraction pattern of the yarn body. Yarn twist is then derived from the measured surface twist angle and yarn diameter. Further studies reveal that the measured yarn twists by the proposed method are comparable to those measured based on microscopic images of the yarn. This method requires no high-magnification optics and is able to pick up short-term variations of twist with less labor intensity, indicating its potential application in the on-line measuring of yarn twist and its distribution.

  6. Understanding nucleic acid structural changes by comparing wide-angle x-ray scattering (WAXS) experiments to molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Pabit, Suzette A.; Katz, Andrea M.; Tolokh, Igor S.; Drozdetski, Aleksander; Baker, Nathan; Onufriev, Alexey V.; Pollack, Lois

    2016-05-01

    Wide-angle x-ray scattering (WAXS) is emerging as a powerful tool for increasing the resolution of solution structure measurements of biomolecules. Compared to its better known complement, small angle x-ray scattering (SAXS), WAXS targets higher scattering angles and can enhance structural studies of molecules by accessing finer details of solution structures. Although the extension from SAXS to WAXS is easy to implement experimentally, the computational tools required to fully harness the power of WAXS are still under development. Currently, WAXS is employed to study structural changes and ligand binding in proteins; however, the methods are not as fully developed for nucleic acids. Here, we show how WAXS can qualitatively characterize nucleic acid structures as well as the small but significant structural changes driven by the addition of multivalent ions. We show the potential of WAXS to test all-atom molecular dynamics (MD) simulations and to provide insight into understanding how the trivalent ion cobalt(III) hexammine (CoHex) affects the structure of RNA and DNA helices. We find that MD simulations capture the RNA structural change that occurs due to addition of CoHex.

  7. 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

  8. Particle sizing by measurement of forward-scattered light at two angles

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1983-01-01

    Fundamental and practical limitations to particle sizing by measurement of forward scattered light are presented. Methods to minimize the limitations are described. Two types of instruments are compared.

  9. Small-angle light scattering from polymer-dispersed liquid-crystal films

    SciTech Connect

    Loiko, V. A. Maschke, U.; Zyryanov, V. Ya.; Konkolovich, A. V.; Misckevich, A. A.

    2008-10-15

    A method is developed for modeling and computing the angular distribution of light scattered forward from a single-layer polymer-dispersed liquid-crystal (PDLC) film. The method is based on effective-medium approximation, anomalous diffraction approximation, and far-field single-scattering approximation. The angular distribution of forward-scattered light is analyzed for PDLC films with droplet size larger than the optical wavelength. The method can be used to study field-and temperature-induced phase transitions in LC droplets with cylindrical symmetry by measuring polarized scattered light intensity.

  10. Distribution angle control of a light-emitting diode downlight lens with high color uniformity using a scattering polymer

    NASA Astrophysics Data System (ADS)

    Mochizuki, Keiichi; Oosumi, Kazumasa; Koizumi, Fumiaki; Shinohara, Yoshinori; Tagaya, Akihiro; Koike, Yasuhiro

    2015-06-01

    We have proposed a light-emitting diode (LED) downlight lens that is made of a highly scattered optical transmission (HSOT) polymer. The HSOT polymer contains optimized heterogeneous structures that produce homogeneously scattered light with forward directivity. The full width at half maximum of the illuminance distribution angle can be increased from 16.7° to 37.9° as the concentration of the scattering particles in the HSOT polymer LED downlight lenses of identical shape is increased from 0.015 to 0.100 wt%. The colors in an illuminated area are highly uniform, which is not discernible by the human eye, with a high output efficiency greater than 85 %.

  11. Cell growth characteristics from angle- and polarization-resolved light scattering: Prospects for two-dimensional correlation analysis

    NASA Astrophysics Data System (ADS)

    Herran Cuspinera, Roxana M.; Hore, Dennis K.

    2016-11-01

    We highlight the potential of generalized two-dimensional correlation analysis for the fingerprinting of cell growth in solution monitored by light scattering, where the synchronous and asynchronous responses serve as a sensitive marker for the effect of growth conditions on the distribution of cell morphologies. The polarization of the scattered light varies according to the cell size distribution, and so the changes in the polarization over time are an excellent indicator of the dynamic growth conditions. However, direct comparison of the polarization-, time-, and angle-resolved signals between different experiments is hindered by the subtle changes in the data, and the inability to easily adapt models to account for these differences. Using Mie scattering simulations of different growth conditions, and some preliminary experimental data for a single set of conditions, we illustrate that correlation analysis provides rapid and sensitive qualitative markers of growth characteristics.

  12. Distribution of Sulfur in Carbon/Sulfur Nanocomposites Analyzed by Small-Angle X-ray Scattering.

    PubMed

    Petzold, Albrecht; Juhl, Anika; Scholz, Jonas; Ufer, Boris; Goerigk, Günter; Fröba, Michael; Ballauff, Matthias; Mascotto, Simone

    2016-03-22

    The analysis of sulfur distribution in porous carbon/sulfur nanocomposites using small-angle X-ray scattering (SAXS) is presented. Ordered porous CMK-8 carbon was used as the host matrix and gradually filled with sulfur (20-50 wt %) via melt impregnation. Owing to the almost complete match between the electron densities of carbon and sulfur, the porous nanocomposites present in essence a two-phase system and the filling of the host material can be precisely followed by this method. The absolute scattering intensities normalized per unit of mass were corrected accounting for the scattering contribution of the turbostratic microstructure of carbon and amorphous sulfur. The analysis using the Porod parameter and the chord-length distribution (CLD) approach determined the specific surface areas and filling mechanism of the nanocomposite materials, respectively. Thus, SAXS provides comprehensive characterization of the sulfur distribution in porous carbon and valuable information for a deeper understanding of cathode materials of lithium-sulfur batteries.

  13. Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data

    PubMed Central

    Putnam, Christopher D.

    2016-01-01

    The Guinier region in small-angle X-ray scattering (SAXS) defines the radius of gyration, R g, and the forward scattering intensity, I(0). In Guinier peak analysis (GPA), the plot of qI(q) versus q 2 transforms the Guinier region into a characteristic peak for visual and automated inspection of data. Deviations of the peak position from the theoretical position in dimensionless GPA plots can suggest parameter errors, problematic low-resolution data, some kinds of intermolecular interactions or elongated scatters. To facilitate automated analysis by GPA, the elongation ratio (ER), which is the ratio of the areas in the pair-distribution function P(r) after and before the P(r) maximum, was characterized; symmetric samples have ER values around 1, and samples with ER values greater than 5 tend to be outliers in GPA analysis. Use of GPA+ER can be a helpful addition to SAXS data analysis pipelines. PMID:27738411

  14. Anomalous small angle x-ray scattering studies of amorphous metal-germanium alloys

    SciTech Connect

    Rice, M.

    1993-12-01

    This dissertation addresses the issue of composition modulation in sputtered amorphous metal-germanium thin films with the aim of understanding the intermediate range structure of these films as a function of composition. The investigative tool used in this work is anomalous small-angle X-ray scattering (ASAXS). The primary focus of this investigation is the amorphous iron-germanium (a-Fe{sub x}Ge{sub 100-x}) system with particular emphasis on the semiconductor-rich regime. Brief excursions are made into the amorphous tungsten-germanium (a-W{sub x}Ge{sub 100-x}) and the amorphous molybdenum-germanium (a-Mo{sub x}Ge{sub 100-x}) systems. All three systems exhibit an amorphous structure over a broad composition range extending from pure amorphous germanium to approximately 70 atomic percent metal when prepared as sputtered films. Across this composition range the structures change from the open, covalently bonded, tetrahedral network of pure a-Ge to densely packed metals. The structural changes are accompanied by a semiconductor-metal transition in all three systems as well as a ferromagnetic transition in the a-Fe{sub x}Ge{sub 100-x} system and a superconducting transition in the a-Mo{sub x}Ge{sub 100-x} system. A long standing question, particularly in the a-Fe{sub x}Ge{sub 100-x} and the a-Mo{sub x}Ge{sub 100-x} systems, has been whether the structural changes (and therefore the accompanying electrical and magnetic transitions) are accomplished by homogeneous alloy formation or phase separation. The application of ASAXS to this problem proves unambiguously that fine scale composition modulations, as distinct from the simple density fluctuations that arise from cracks and voids, are present in the a-Fe{sub x}Ge{sub 100-x}, a-W{sub x}Ge{sub 100-x}, and a-Mo{sub x}Ge{sub 100-x} systems in the semiconductor-metal transition region. Furthermore, ASAXS shows that germanium is distributed uniformly throughout each sample in the x<25 regime of all three systems.

  15. Structural behaviour of mixed cationic surfactant micelles: a small-angle neutron scattering study.

    PubMed

    Bergström, L Magnus; Garamus, Vasil M

    2012-09-01

    Self-assembly in mixtures of two single-chain cationic surfactants, with different tail lengths (CTAB and DTAB) as well as of a single-chain (DTAB) and a double-chain (DDAB) cationic surfactant, with identical tail lengths, have been investigated with small-angle neutron scattering (SANS) and rationalised in terms of bending elasticity properties. The growth behaviour of micelles with respect to surfactant composition appears completely different in the two surfactant mixtures. DTAB form small oblate spheroidal micelles in presence of [NaBr]=0.1 M that transform into prolate spheroidal mixed CTAB/DTAB micelles upon adding moderate amounts of CTAB, so as to give a mole fraction y=0.20 in solution. Most unexpectedly, upon further addition of CTAB the mixed CTAB/DTAB micelles grow with an almost equal rate in both length and width directions to form tablets. In contrast to this behaviour, mixed DDAB/DTAB micelles grow virtually exclusively in the length direction, in presence of [NaBr]=0.1 M, to form elongated ellipsoidal (tablet-shaped) and subsequently long wormlike micelles as the fraction of DDAB in the micelles increases. Mixed DDAB/DTAB micelles grow to become as long as 2000Å before an abrupt transition to large bilayer structures occurs. This means that the micelles are much longer at the micelle-to-bilayer transition as compared to the same mixture in absence of added salt. It is found that the point of transition from micelles to bilayers is significantly shifted towards higher fractions of aggregated DTAB as an appreciable amount of salt is added to DDAB/DTAB mixtures, indicating a considerable reduction of the spontaneous curvature with an increasing [NaBr]. By means of deducing the various bending elasticity constants from our experimental results, according to a novel approach by ours, we are able to conclude that the different growth behaviours appear as a consequence of a considerably lower bending rigidity, as well as higher saddle-splay constant

  16. Design of Ultra Small Angle Neutron Scattering (KIST-USANS) at HANARO Cold Neutron Guide, CG4B

    NASA Astrophysics Data System (ADS)

    Kim, Man-Ho

    2013-03-01

    The ultra small angle neutron scattering instrument can measure the lower limit of scattering vector to near Q ~ 2.0x10-5 Å-1 while the upper limit can reach to an intermediate scattering vector Q ~ 10-2 Å-1 of a typical small angle neutron scattering (SANS) depending on the contrast of sample. USANS is useful when measuring objects that are micron to submicron in size while SANS is useful when measuring objects that are micron to nano in size. When both USANS and SANS were used together, we could measure sizes from micron to nano scale, which is useful when studying the hierarchical structures in the wide scale of Q and total cross-section, d Σ/d Ω(Q). Recently, KIST has developed the USANS (so called KIST-USANS) at HANARO cold neutron guide hall of KAERI. We will present the instrument design, performance, future plan, and some examples of measurements that cover approximately 11 orders of magnitude in the d Σ/d Ω(Q) and 4 orders in the Q. This work was partially supported by the KIST (2v02632) and the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2012M2B2A4030220)

  17. The Fokker-Planck coefficient for pitch-angle scattering of cosmic rays. [considering magnetic field fluctuations

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.; Goldstein, M. L.; Klimas, A. J.; Sandri, G.

    1973-01-01

    For the case of homogeneous, isotropic magnetic field fluctuations, it is shown that most theories which are based on the quasi-linear and adiabatic approximation yield the same integral for the Fokker-Planck coefficient for the pitch angle scattering of cosmic rays. For example, despite apparent differences, the theories due to Jokipii and to Klimas and Sandri yield the same integral. It is also shown, however, that this integral in most cases has been evaluated incorrectly in the past. For large pitch angles these errors become significant, and for pitch angles of 90 deg the actual Fokker-Planck coefficient contains a delta function. The implications for these corrections relating cosmic ray diffusion coefficients to observed properties of the interplanetary magnetic field are discussed.

  18. Determination of soot scattering coefficient from extinction and three-angle scattering in a laminar diffusion flame

    SciTech Connect

    Iyer, Suresh S.; Litzinger, Thomas A.; Lee, Seong-Young; Santoro, Robert J.

    2007-04-15

    The total scattering coefficient is determined from three multiangle scattering measurements at different heights above the burner in a nonsooting laminar ethylene diffusion flame. The local extinction coefficient is determined from multichord extinction measurements. The above analysis quantifies the contribution from scattering to extinction without knowledge of the soot primary particle diameter or the morphology of the aggregates, and the absorption coefficient can now be determined. The primary particle diameter, the number density of primary particles, the average number of primary particles in an aggregate, and the width of the lognormal distribution function for the number of primary particles in an aggregate are calculated using the absorption coefficient and assumed constant values for the fractal dimension, the fractal prefactor, and the complex refractive index for soot. The values for the primary particle diameter obtained from the in situ measurements in this study compare well with those obtained from transmission electron microscopic measurements of thermophoretically sampled soot aggregates in a previous study at all heights in the diffusion flame, while the calculated soot structure parameters compare well with previous studies only at heights between 30 and 50 mm above the burner. (author)

  19. Gated cardiac scanning using limited-angle image reconstruction technique and information in the neighboring phases

    SciTech Connect

    Tam, K.C.; MacDonald, B.; Perez-Mendez, V.

    1984-02-01

    It is known that there are gaps in scan angle in gated cardiac scanning due to lack of synchronization between heart beat and CT machine rotation. The missing projections in these gaps result in artifacts in the reconstructed images. In a previous paper an iterative limited-angle reconstruction technique was employed to fill in the missing projections to remove the artifacts. It was found there that the root-mean-square errors of the limited-angle images were reduced to a level comparable to those of reconstructions using complete-angle information. In the present paper the results are further improved by using the scans of a neighboring portion of the cardiac cycle as a first estimate of the missing scans in the phase of interest when initializing the iterations. Such a modification provides a better starting point for the iterations.

  20. Crystallization of a layered silicate clay as monitored by small- angle x-ray scattering and NMR.

    SciTech Connect

    Carrado, K. A.; Xu, L.; Gregory, D.; Song, K.; Seifert, S.; Botto, R. E.; Chemistry

    2000-10-01

    The 48-h hydrothermal crystallization of a magnesium silicate clay called hectorite has been investigated in detail. Tetraethylammonium (TEA) ions are used to aid crystallization and become incorporated as the exchange cations within the interlayers. Data from small-angle X-ray scattering (SAXS) using aliquots ex situ are consistent with results obtained previously by X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), atomic force microscopy (AFM), and IR. All these techniques see clay crystallites beginning to form within the first few hours of reaction. {sup 29}Si NMR displays a visible clay silicate peak after just 1 h. Solid-state {sup 13}C NMR shows evidence of TEA-clay formation in as little as 30 min and also that 80% of the final TEA loading is accomplished in the first 10-12 h. Up to 36 h more is needed to incorporate the remaining 20% of TEA, indicating that a slower event is dominating at the later stages of crystallization. Data from {sup 13}C NMR and SAXS are compared to and are consistent with data from earlier AFM experiments. All present a scenario where initial nucleation and crystallization end after about 14 h, after which this occurs to a lesser extent and primarily agglomeration of particles is taking place. The SAXS data show this in progressively increasing power law values, indicating more 'open' structures that condense into more dense structures with time. In addition, the first in situ study of clay crystallization of any kind was performed by in situ SAXS. A possible clay crystallization mechanism is proposed.