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1
GOYAL, P. S., e V. K. ASWAL. "USE OF SANS AND SAXS IN STUDY OF NANOPARTICLES". International Journal of Nanoscience 04, n. 05n06 (ottobre 2005): 987–94. http://dx.doi.org/10.1142/s0219581x05003954.
Testo completoAbstract (sommario):
Small Angle Neutron Scattering (SANS) and Small Angle X-ray Scattering (SAXS), anong other available techniques, are the nost sought after techniques for studying the sizes and shapes of nanoparticles. The contrast between particle and its surrounding is different for X-rays and neutrons. Thus a combined SANS and SAXS study, at times, provides information about the core and the shell structure of nanoparticles. This paper gives an introduction to the techniques of SANS and SAXS and shows results of a study of core-shell structure for a micelle (nanaoparticle of organic material).
2
Härk, Eneli, e Matthias Ballauff. "Carbonaceous Materials Investigated by Small-Angle X-ray and Neutron Scattering". C 6, n. 4 (19 dicembre 2020): 82. http://dx.doi.org/10.3390/c6040082.
Testo completoAbstract (sommario):
Carbonaceous nanomaterials have become important materials with widespread applications in battery systems and supercapacitors. The application of these materials requires precise knowledge of their nanostructure. In particular, the porosity of the materials together with the shape of the pores and the total internal surface must be known accurately. Small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) present the methods of choice for this purpose. Here we review our recent investigations using SAXS and SANS. We first describe the theoretical basis of the analysis of carbonaceous material by small-angle scattering. The evaluation of the small-angle data relies on the powerful concept of the chord length distribution (CLD) which we explain in detail. As an example of such an evaluation, we use recent analysis by SAXS of carbide-derived carbons. Moreover, we present our SAXS analysis on commercially produced activated carbons (ACN, RP-20) and provide a comparison with small-angle neutron scattering data. This comparison demonstrates the wealth of additional information that would not be obtained by the application of either method alone. SANS allows us to change the contrast, and we summarize the main results using different contrast matching agents. The pores of the carbon nanomaterials can be filled gradually by deuterated p-xylene, which leads to a precise analysis of the pore size distribution. The X-ray scattering length density of carbon can be matched by the scattering length density of sulfur, which allows us to see the gradual filling of the nanopores by sulfur in a melt-impregnation procedure. This process is important for the application of carbonaceous materials as cathodes in lithium/sulfur batteries. All studies summarized in this review underscore the great power and precision with which carbon nanomaterials can be analyzed by SAXS and SANS.
3
Allen, Andrew J., Fan Zhang, R. Joseph Kline, William F. Guthrie e Jan Ilavsky. "NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering". Journal of Applied Crystallography 50, n. 2 (7 marzo 2017): 462–74. http://dx.doi.org/10.1107/s1600576717001972.
Testo completoAbstract (sommario):
The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certifiedQrange,Q= 0.008–0.25 Å−1, together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments that employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. The validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.
4
Sreij, Ramsia, Carina Dargel, Philippe Geisler, Yvonne Hertle, Aurel Radulescu, Stefano Pasini, Javier Perez, Lara H. Moleiro e Thomas Hellweg. "DMPC vesicle structure and dynamics in the presence of low amounts of the saponin aescin". Physical Chemistry Chemical Physics 20, n. 14 (2018): 9070–83. http://dx.doi.org/10.1039/c7cp08027a.
Testo completoAbstract (sommario):
Vesicle shape and bilayer parameters are studied by small-angle X-ray (SAXS) and small-angle neutron (SANS) scattering in the presence of the saponin aescin. Bilayer dynamics is studied by neutron spin-echo (NSE) spectroscopy.
5
Allen, Andrew J. "Selected advances in small-angle scattering and applications they serve in manufacturing, energy and climate change". Journal of Applied Crystallography 56, n. 3 (29 maggio 2023): 787–800. http://dx.doi.org/10.1107/s1600576723003898.
Testo completoAbstract (sommario):
Innovations in small-angle X-ray and neutron scattering (SAXS and SANS) at major X-ray and neutron facilities offer new characterization tools for researching materials phenomena relevant to advanced applications. For SAXS, the new generation of diffraction-limited storage rings, incorporating multi-bend achromat concepts, dramatically decrease electron beam emittance and significantly increase X-ray brilliance over previous third-generation sources. This results in intense X-ray incident beams that are more compact in the horizontal plane, allowing significantly improved spatial resolution, better time resolution, and a new era for coherent-beam SAXS methods such as X-ray photon correlation spectroscopy. Elsewhere, X-ray free-electron laser sources provide extremely bright, fully coherent, X-ray pulses of <100 fs and can support SAXS studies of material processes where entire SAXS data sets are collected in a single pulse train. Meanwhile, SANS at both steady-state reactor and pulsed spallation neutron sources has significantly evolved. Developments in neutron optics and multiple detector carriages now enable data collection in a few minutes for materials characterization over nanometre-to-micrometre scale ranges, opening up real-time studies of multi-scale materials phenomena. SANS at pulsed neutron sources is becoming more integrated with neutron diffraction methods for simultaneous structure characterization of complex materials. In this paper, selected developments are highlighted and some recent state-of-the-art studies discussed, relevant to hard matter applications in advanced manufacturing, energy and climate change.
6
Murthy, N. Sanjeeva, Zheng Zhang, Siddharth Borsadia e Joachim Kohn. "Nanospheres with a smectic hydrophobic core and an amorphous PEG hydrophilic shell: structural changes and implications for drug delivery". Soft Matter 14, n. 8 (2018): 1327–35. http://dx.doi.org/10.1039/c7sm02472j.
Testo completoAbstract (sommario):
The structural changes in nanospheres with a crystalline core and an amorphous diffuse shell were investigated by small-angle neutron scattering (SANS), small-, medium-, and wide-angle X-ray scattering (SAXS, MAXS and WAXS), and differential scanning calorimetry (DSC).
7
Lamparter, P., e B. Boucher. "Small Angle Neutron Scattering with Hydrogenated Amorphous Cu50 Ti50 and Ni-Ti-Si Alloys". Zeitschrift für Naturforschung A 48, n. 11 (1 novembre 1993): 1086–92. http://dx.doi.org/10.1515/zna-1993-1105.
Testo completoAbstract (sommario):
Abstract The metallic glasses Cu50Ti50, Ni30Ti60Si10, Ni32Ti52Si16 , Ni16Ti68Si16 and Ti84Si16 were produced by melt spinning. The alloys in the blank state as well as after loading with hydrogen or deuterium were investigated by small angle neutron (SANS) and X-ray (SAXS) scattering. The scattering of the different amorphous alloys exhibited common features. SANS follows a power-law with exponent of the scattering vector between -3 and -4. The melt-spun glasses contain extended structural inhomogeneities which are associated rather with the local composition than with the local density. SAXS measurements did not show effects above the background level. Loading the alloys with hydrogen or deuterium causes strong effects in the SANS behaviour. From the results it is concluded that the amorphous alloys contain inner surfaces where the hydrogen atoms segregate.
8
Kalus, J., e U. Schmelzer. "Small angle neutron (SANS) and x-ray (SAXS) scattering on micellar systems". Physica Scripta T49B (1 gennaio 1993): 629–35. http://dx.doi.org/10.1088/0031-8949/1993/t49b/042.
Testo completo
9
Metwalli, Ezzeldin, Klaus Götz, Sebastian Lages, Christian Bär, Tobias Zech, Dennis M. Noll, Isabel Schuldes et al. "A novel experimental approach for nanostructure analysis: simultaneous small-angle X-ray and neutron scattering". Journal of Applied Crystallography 53, n. 3 (13 maggio 2020): 722–33. http://dx.doi.org/10.1107/s1600576720005208.
Testo completoAbstract (sommario):
Exploiting small-angle X-ray and neutron scattering (SAXS/SANS) on the same sample volume at the same time provides complementary nanoscale structural information in two different contrast situations. Unlike an independent experimental approach, the truly combined SAXS/SANS experimental approach ensures the exactness of the probed samples, particularly for in situ studies. Here, an advanced portable SAXS system that is dimensionally suitable for installation in the D22 zone of ILL is introduced. The SAXS apparatus is based on a Rigaku switchable copper/molybdenum microfocus rotating-anode X-ray generator and a DECTRIS detector with a changeable sample-to-detector distance of up to 1.6 m in a vacuum chamber. A case study is presented to demonstrate the uniqueness of the newly established method. Temporal structural rearrangements of both the organic stabilizing agent and organically capped gold colloidal particles during gold nanoparticle growth are simultaneously probed, enabling the immediate acquisition of correlated structural information. The new nano-analytical method will open the way for real-time investigations of a wide range of innovative nanomaterials and will enable comprehensive in situ studies on biological systems. The potential development of a fully automated SAXS/SANS system with a common control environment and additional sample environments, permitting a continual and efficient operation of the system by ILL users, is also introduced.
10
Mahieu, Emilie, e Frank Gabel. "Biological small-angle neutron scattering: recent results and development". Acta Crystallographica Section D Structural Biology 74, n. 8 (17 luglio 2018): 715–26. http://dx.doi.org/10.1107/s2059798318005016.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) has increasingly been used by the structural biology community in recent years to obtain low-resolution information on solubilized biomacromolecular complexes in solution. In combination with deuterium labelling and solvent-contrast variation (H2O/D2O exchange), SANS provides unique information on individual components in large heterogeneous complexes that is perfectly complementary to the structural restraints provided by crystallography, nuclear magnetic resonance and electron microscopy. Typical systems studied include multi-protein or protein–DNA/RNA complexes and solubilized membrane proteins. The internal features of these systems are less accessible to the more broadly used small-angle X-ray scattering (SAXS) technique owing to a limited range of intra-complex and solvent electron-density variation. Here, the progress and developments of biological applications of SANS in the past decade are reviewed. The review covers scientific results from selected biological systems, including protein–protein complexes, protein–RNA/DNA complexes and membrane proteins. Moreover, an overview of recent developments in instruments, sample environment, deuterium labelling and software is presented. Finally, the perspectives for biological SANS in the context of integrated structural biology approaches are discussed.
11
Johansen, Nicolai Tidemand, Martin Cramer Pedersen, Lionel Porcar, Anne Martel e Lise Arleth. "Introducing SEC–SANS for studies of complex self-organized biological systems". Acta Crystallographica Section D Structural Biology 74, n. 12 (30 novembre 2018): 1178–91. http://dx.doi.org/10.1107/s2059798318007180.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) is maturing as a method for studying complex biological structures. Owing to the intrinsic ability of the technique to discern between 1H- and 2H-labelled particles, it is especially useful for contrast-variation studies of biological systems containing multiple components. SANS is complementary to small-angle X-ray scattering (SAXS), in which similar contrast variation is not easily performed but in which data with superior counting statistics are more easily obtained. Obtaining small-angle scattering (SAS) data on monodisperse complex biological structures is often challenging owing to sample degradation and/or aggregation. This problem is enhanced in the D2O-based buffers that are typically used in SANS. In SAXS, such problems are solved using an online size-exclusion chromatography (SEC) setup. In the present work, the feasibility of SEC–SANS was investigated using a series of complex and difficult samples of membrane proteins embedded in nanodisc particles that consist of both phospholipid and protein components. It is demonstrated that SEC–SANS provides data of sufficient signal-to-noise ratio for these systems, while at the same time circumventing aggregation. By combining SEC–SANS and SEC–SAXS data, an optimized basis for refining structural models of the investigated structures is obtained.
12
Honaramooz, Mohammad Taha, Roland Morak, Stefan Pogatscher, Gerhard Fritz-Popovski, Thomas M. Kremmer, Thomas C. Meisel, Johannes A. Österreicher, Aurel Arnoldt e Oskar Paris. "Characterization of Zr-Containing Dispersoids in Al–Zn–Mg–Cu Alloys by Small-Angle Scattering". Materials 16, n. 3 (31 gennaio 2023): 1213. http://dx.doi.org/10.3390/ma16031213.
Testo completoAbstract (sommario):
The characterization of Zr-containing dispersoids in aluminum alloys is challenging due to their broad size distribution, low volume fraction, and heterogeneous distribution within the grains. In this work, small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) were compared to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) regarding their capability to characterize Zr-containing dispersoids in aluminum alloys. It was demonstrated that both scattering techniques are suitable tools to characterize dispersoids in a multi-phase industrial 7xxx series aluminum alloy. While SAXS is more sensitive than SANS due to the high electron density of Zr-containing dispersoids, SANS has the advantage of being able to probe a much larger sample volume. The combination of both scattering techniques allows for the verification that the contribution from dispersoids can be separated from that of other precipitate phases such as the S-phase or GP-zones. The size distributions obtained from SAXS, SANS and TEM showed good agreement. The SEM-derived size distributions were, however, found to significantly deviate from those of the other techniques, which can be explained by considering the resolution-limited restrictions of the different techniques.
13
Stuhrmann, Heinrich B. "Small-angle scattering and its interplay with crystallography, contrast variation in SAXS and SANS". Acta Crystallographica Section A Foundations of Crystallography 64, n. 1 (21 dicembre 2007): 181–91. http://dx.doi.org/10.1107/s0108767307046569.
Testo completoAbstract (sommario):
Methods of contrast variation are tools that are essential in macromolecular structure research. Anomalous dispersion of X-ray diffraction is widely used in protein crystallography. Recent attempts to extend this method to native resonant labels like sulfur and phosphorus are promising. Substitution of hydrogen isotopes is central to biological applications of neutron scattering. Proton spin polarization considerably enhances an existing contrast prepared by isotopic substitution. Concepts and methods of nuclear magnetic resonance (NMR) become an important ingredient in neutron scattering from dynamically polarized targets.
14
Mahieu, Emilie, Ziad Ibrahim, Martine Moulin, Michael Härtlein, Bruno Franzetti, Anne Martel e Frank Gabel. "The power of SANS, combined with deuteration and contrast variation, for structural studies of functional and dynamic biomacromolecular systems in solution". EPJ Web of Conferences 236 (2020): 03002. http://dx.doi.org/10.1051/epjconf/202023603002.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS), combined with macromolecular deuteration and solvent contrast variation (H2O/D2O exchange) allows focussing selectively on the signal of specific proteins in multi-protein complexes or mixtures of isolated proteins. We illustrate this unique capacity by the example of a functional protein-degradation system in solution, the PAN-20S proteasome complex in the presence of a protein substrate, ssrA-tagged GFP. By comparing experimental SANS data with synthetic SAXS (small-angle X-ray scattering) data, predicted for the same system under identical conditions, we show that SANS, when combined with macromolecular deuteration and solvent contrast variation, can specifically focus on the conformation of the PAN unfoldase, even in the presence of very large GFP aggregates. Likewise, structural information of native GFP states can be visualized in detail, even in the presence of the much larger PAN-20S unfoldase-protease oligomers, which would dominate the overall scattering signal when using X-rays instead of neutrons.
15
Butter, Karen, Armin Hoell, Albrecht Wiedenmann, Andrei V. Petukhov e Gert-Jan Vroege. "Small-angle neutron and X-ray scattering of dispersions of oleic-acid-coated magnetic iron particles". Journal of Applied Crystallography 37, n. 6 (11 novembre 2004): 847–56. http://dx.doi.org/10.1107/s0021889804018564.
Testo completoAbstract (sommario):
This paper describes the characterization of dispersions of oleic-acid-coated magnetic iron particles by small-angle neutron and X-ray scattering (SANS and SAXS). Both oxidized and non-oxidized dilute samples were studied by SANS at different contrasts. The non-oxidized samples are found to consist of non-interacting superparamagnetic single dipolar particles, with a lognormal distribution of iron cores, surrounded by a surfactant shell, which is partially penetrated by solvent. This model is supported by SAXS measurements on the same dispersion. Small iron particles are expected to oxidize upon exposure to air. SANS was used to study the effect of this oxidation, both on single particles, as well as on interparticle interactions. It is found that on exposure to air, a non-magnetic oxide layer is formed around the iron cores, which causes an increase of particle size. In addition, particles are found to aggregate upon oxidation, presumably because the surfactant density on the particle surfaces is decreased.
16
Hinde, Alan L. "PRINSAS– a Windows-based computer program for the processing and interpretation of small-angle scattering data tailored to the analysis of sedimentary rocks". Journal of Applied Crystallography 37, n. 6 (11 novembre 2004): 1020–24. http://dx.doi.org/10.1107/s0021889804021260.
Testo completoAbstract (sommario):
PRINSASis a Windows program that takes as input raw (post-reduction) small-angle neutron and small-angle X-ray scattering (SANS and SAXS) data obtained from various worldwide facilities, displays the raw curves in interactive log–log plots, and allows processing of the raw curves. Separate raw SANS and ultra-small-angle neutron scattering (USANS) curves can be combined into complete scattering curves for an individual sample. The combined curves can be interpreted and information inferred about sample structure, using built-in functions. These have been tailored for geological samples and other porous media, and include the ability to obtain an arbitrary distribution of scatterer sizes, the corresponding specific surface area of scatterers, and porosity (when the scatterers are pores), assuming spherical scatterers. A fractal model may also be assumed and the fractal dimension obtained. A utility for calculating scattering length density from the component oxides is included in the program.
17
Keshari, Ashish K., e Avinash C. Pandey. "Size and Distribution: A Comparison of XRD, SAXS and SANS Study of II–VI Semiconductor Nanocrystals". Journal of Nanoscience and Nanotechnology 8, n. 3 (1 marzo 2008): 1221–27. http://dx.doi.org/10.1166/jnn.2008.370.
Testo completoAbstract (sommario):
The uniqueness of size dependent functional properties of II–VI semiconductor nanocrystals have led to the development of various techniques for determination of shape, size and distributions, although the accurate measurements of the particle sizes has always been a fundamental task in nanoscience and even become more crucial with the discovery of quantum confinement effect. Acomparison of the well established techniques X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) with an emphasis on size and distribution of the prepared samples are reported in order to elaborate more precise techniques for the analysis of particles sizes. Modified Scherrer formula for spherical particles has been used to calculate the particle sizes from XRD spectra. Analysis of SAXS data has been reported using Guinier model. Small angle neutron scattering measurements has been performed for ZnO nanocrystals and the scattering data obtained is simulated for polydisperse sphere. The bare ZnO, ZnS and CdS and doped with Mn2+ systems are taken within the framework of our discussion. These materials were synthesized by chemical precipitation route and found to have size distribution from 2 to 6 nm for spherical particles. Sizes determined from various techniques are in good agreement with each other however small angle scattering technique is more reliable than XRD to determine the sizes of the nanoparticles.
18
Semeraro, Enrico F., Juliette M. Devos, Lionel Porcar, V. Trevor Forsyth e Theyencheri Narayanan. "In vivoanalysis of theEscherichia coliultrastructure by small-angle scattering". IUCrJ 4, n. 6 (26 settembre 2017): 751–57. http://dx.doi.org/10.1107/s2052252517013008.
Testo completoAbstract (sommario):
The flagellated Gram-negative bacteriumEscherichia coliis one of the most studied microorganisms. Despite extensive studies as a model prokaryotic cell, the ultrastructure of the cell envelope at the nanometre scale has not been fully elucidated. Here, a detailed structural analysis of the bacterium using a combination of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) and ultra-SAXS (USAXS) methods is presented. A multiscale structural model has been derived by incorporating well established concepts in soft-matter science such as a core-shell colloid for the cell body, a multilayer membrane for the cell wall and self-avoiding polymer chains for the flagella. The structure of the cell envelope was resolved by constraining the model by five different contrasts from SAXS, and SANS at three contrast match points and full contrast. This allowed the determination of the membrane electron-density profile and the inter-membrane distances on a quantitative scale. The combination of USAXS and SAXS covers size scales from micrometres down to nanometres, enabling the structural elucidation of cells from the overall geometry down to organelles, thereby providing a powerful method for a non-invasive investigation of the ultrastructure. This approach may be applied for probingin vivothe effect of detergents, antibiotics and antimicrobial peptides on the bacterial cell wall.
19
Golub, Maksym, e Jörg Pieper. "Recent Progress in Solution Structure Studies of Photosynthetic Proteins Using Small-Angle Scattering Methods". Molecules 28, n. 21 (3 novembre 2023): 7414. http://dx.doi.org/10.3390/molecules28217414.
Testo completoAbstract (sommario):
Utilized for gaining structural insights, small-angle neutron and X-ray scattering techniques (SANS and SAXS, respectively) enable an examination of biomolecules, including photosynthetic pigment-protein complexes, in solution at physiological temperatures. These methods can be seen as instrumental bridges between the high-resolution structural information achieved by crystallography or cryo-electron microscopy and functional explorations conducted in a solution state. The review starts with a comprehensive overview about the fundamental principles and applications of SANS and SAXS, with a particular focus on the recent advancements permitting to enhance the efficiency of these techniques in photosynthesis research. Among the recent developments discussed are: (i) the advent of novel modeling tools whereby a direct connection between SANS and SAXS data and high-resolution structures is created; (ii) the employment of selective deuteration, which is utilized to enhance spatial selectivity and contrast matching; (iii) the potential symbioses with molecular dynamics simulations; and (iv) the amalgamations with functional studies that are conducted to unearth structure-function relationships. Finally, reference is made to time-resolved SANS/SAXS experiments, which enable the monitoring of large-scale structural transformations of proteins in a real-time framework.
20
Buckley, C. E., H. K. Birnbaum, J. S. Lin, S. Spooner, D. Bellmann, P. Staron, T. J. Udovic e E. Hollar. "Characterization of H defects in the aluminium–hydrogen system using small-angle scattering techniques". Journal of Applied Crystallography 34, n. 2 (1 aprile 2001): 119–29. http://dx.doi.org/10.1107/s0021889800018239.
Testo completoAbstract (sommario):
Aluminium foils (99.99% purity) and single crystals (99.999% purity) were charged with hydrogen using a gas plasma method and electrochemical methods, resulting in the introduction of a large amount of hydrogen. X-ray diffraction measurements indicated that within experimental error there was a zero change in lattice parameter after plasma charging. This result is contradictory to almost all other face-centred cubic (f.c.c.) materials, which exhibit a lattice expansion when the hydrogen enters the lattice interstitially. It is hypothesized that the hydrogen does not enter the lattice as an interstitial solute, but instead forms an H–vacancy complex at the surface that diffuses into the volume and then clusters to form H2bubbles. Small- and ultra-small-angle neutron scattering (SANS, USANS) and small-angle X-ray scattering (SAXS) were primarily employed to study the nature and agglomeration of the H–vacancy complexes in the Al–H system. The SAXS results were ambiguous owing to double Bragg scattering, but the SANS and USANS investigation, coupled with results from inelastic neutron scattering, and transmission and scanning electron microscopy, revealed the existence of a large size distribution of hydrogen bubbles on the surface and in the bulk of the Al–H system. The relative change in lattice parameter is calculated from the pressure in a bubble of average volume and is compared with the experimentally determined value.
21
Sato, Nobuhiro, Rina Yogo, Saeko Yanaka, Anne Martel, Lionel Porcar, Ken Morishima, Rintaro Inoue et al. "A feasibility study of inverse contrast-matching small-angle neutron scattering method combined with size exclusion chromatography using antibody interactions as model systems". Journal of Biochemistry 169, n. 6 (2 febbraio 2021): 701–8. http://dx.doi.org/10.1093/jb/mvab012.
Testo completoAbstract (sommario):
Abstract Small-angle neutron scattering (SANS) and small- angle X-ray scattering (SAXS) are powerful techniques for the structural characterization of biomolecular complexes. In particular, SANS enables a selective observation of specific components in complexes by selective deuteration with contrast-matching techniques. In most cases, however, biomolecular interaction systems with heterogeneous oligomers often contain unfavorable aggregates and unbound species, hampering data interpretation. To overcome these problems, SAXS has been recently combined with size exclusion chromatography (SEC), which enables the isolation of the target complex in a multi-component system. By contrast, SEC–SANS is only at a preliminary stage. Hence, we herein perform a feasibility study of this method based on our newly developed inverse contrast-matching (iCM) SANS technique using antibody interactions as model systems. Immunoglobulin G (IgG) or its Fc fragment was mixed with 75% deuterated Fc-binding proteins, i.e. a mutated form of IgG-degrading enzyme of Streptococcus pyogenes and a soluble form of Fcγ receptor IIIb, and subjected to SEC–SANS as well as SEC–SAXS as reference. We successfully observe SANS from the non-deuterated IgG or Fc formed in complex with these binding partners, which were unobservable in terms of SANS in D2O, hence demonstrating the potential utility of the SEC–iCM–SANS approach.
22
Fritz, Gerhard, e Alexander Bergmann. "Interpretation of small-angle scattering data of inhomogeneous ellipsoids". Journal of Applied Crystallography 37, n. 5 (11 settembre 2004): 815–22. http://dx.doi.org/10.1107/s0021889804017959.
Testo completoAbstract (sommario):
Small-angle scattering data of inhomogeneous ellipsoidal particles are discussed in terms of their pair distance distribution functionsp(r). Special attention is given to the determination of core and shell thicknesses and axis ratios as well as to large distances within the particles, since cross terms between parts of positive and negative contrast within the particle can produce misleading results, similar to homogeneous particles or Janus particles. Cross-section pair distance distribution functionspc(r) of cylinders with elliptical cross sections show similar behaviour. Theoretical calculations are compared with small-angle X-ray and neutron scattering (SAXS and SANS) data of cetyltrimethylammonium bromide in aqueous KCl solutions.
23
Gobato, Ricardo, Marcia Regina Risso Gobato, Alireza Heidari e Abhijit Mitra. "Unrestricted hartree-fock computational simulation in a protonated rhodochrosite crystal". Physics & Astronomy International Journal 3, n. 6 (6 novembre 2019): 220–28. http://dx.doi.org/10.15406/paij.2019.03.00187.
Testo completoAbstract (sommario):
In this paper, compact effective potentials, charge distribution, Atomic Polar Tensor (APT) and Mulliken charges were studied using a unrestricted Hartree-Fock computational simulation in a protonated rhodochrosite crystal. The rhodochrosite crystal unit cell of structure CMn6O8, where the charge distribution by the molecule was verified in the UHF CEP-4G (Effective core potential (ECP) minimal basis), UHF CEP-31G (ECP split valance) and UHF CEP-121G (ECP triple-split basis). The largest load variation in the APT and Mulliken methods were obtained in the CEP-121G basis set, with δ=2.922 e δ=2.650 u.a., respectively, being δAPT> δMulliken. The maximum absorbance peaks in the CEP-4G, CEP-31G and CEP-121G basis set are present at the frequencies 2172.23 cm-1, with a normalized intensity of 0.65; 2231.4 cm-1 and 0.454; and 2177.24 cm-1 and 1.0, respectively. An in-depth study is necessary to verify the absorption by the tumoral and non-tumoral tissues of rhodochrosite, before and after irradiating of synchrotron radiation using Small–Angle X–Ray Scattering (SAXS), Ultra–Small Angle X–Ray Scattering (USAXS), Fluctuation X–Ray Scattering (FXS), Wide–Angle X–Ray Scattering (WAXS), Grazing–Incidence Small–Angle X–Ray Scattering (GISAXS), Grazing–Incidence Wide–Angle X–Ray Scattering (GIWAXS), Small–Angle Neutron Scattering (SANS), Grazing–Incidence Small–Angle Neutron Scattering (GISANS), X–Ray Diffraction (XRD), Powder X–Ray Diffraction (PXRD), Wide–Angle X–Ray Diffraction (WAXD), Grazing– Incidence X–Ray Diffraction (GIXD) and Energy–Dispersive X–Ray Diffraction (EDXRD). Later studies could check the advantages and disadvantages of rhodochrosite in the treatment of cancer through synchrotron radiation, such as one oscillator crystal.
24
Allen, Andrew, Fan Zhang, Lyle Levine e Jan Ilavsky. "Towards in operando material process characterization over many length scales". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C1171. http://dx.doi.org/10.1107/s2053273314088287.
Testo completoAbstract (sommario):
The properties and performance of complex material systems are frequently controlled by phenomena that operate over many length-scales from sub-nanometers to millimeters. Understanding the behavior of such materials requires statistically-representative measurement of these effects on the structure and microstructure evolution across this entire length-scale range, over timescales that match those of the phenomena of interest. Small-angle X-ray and neutron scattering (SAXS and SANS) can address much of this need and reveal cause-and-effect phenomena acting across many length scales. This is especially true if SAXS or SANS are combined with wide-angle X-ray and neutron scattering (WAXS and WANS) diffraction measurements to follow the corresponding phase evolution. These concepts are demonstrated in several high-impact studies pursued with our collaborators, including in operando studies to measure: the effects of gas sorption on the structures and microstructures of new carbon sorbent materials [1]; precipitate formation and growth, together with associated phase transformations in advanced light-weight alloys during annealing or plastic deformation; real-time dissolution, clustering and agglomeration of silver nanoparticles in an acidic environment (relevant to environmental health and safety concerns) [2]; and even cement hydration phenomena related to concrete shrinkage. Many of these measurements were made at the ultra-small-angle X-ray scattering (USAXS) facility at the Advanced Photon Source where rapid combined USAXS/SAXS/WAXS studies are now possible under in operando conditions. Planned further development of the instrument capabilities will significantly enhance such in operando measurements, as can be demonstrated by the impact on these same studies [3].
25
Wignall, George D., e Frank S. Bates. "Neutron Scattering in Materials Science: Small-Angle Neutron Scattering Studies of Polymers". MRS Bulletin 15, n. 11 (novembre 1990): 73–77. http://dx.doi.org/10.1557/s0883769400058395.
Testo completoAbstract (sommario):
Before the application of small-angle neutron scattering (SANS) to the study of polymer structure, chain conformation studies were limited to light scattering and small-angle x-ray scattering (SAXS) techniques. These experiments were usually conducted in dilute solution, and the methodology to measure radii of gyration, virial coefficients, molecular weights, etc., was well established in the classical works of Guinier, Zimm, Debye and Kratky, who pioneered these techniques during the 1940s and 1950s. This methodology could not be applied to concentrated solutions or bulk polymers because of the difficulty of separating the intra- and inter-molecular components of the scattering function. One attempt to circumvent this difficulty was the experiment by Krigbaum and Godwin, who end-labeled polystyrene molecules with Ag atoms. When dispersed in unlabeled polystyrene, the excess x-ray scattering could in principle be analyzed to provide the end-to-end distance, though in practice the signal-to-noise ratio of the experiment was insufficient for accurately determining this parameter. To our knowledge the first suggestion to use the difference in coherent scattering lengths of deuterium (bD = 0.66 × 10−12cm) and hydrogen (bH = −0.37 × 10−12cm) to create scattering contrast between deuterated and normal (hydrogenous) molecules and provide a direct determination of molecular dimensions was made independently by at least two groups in the late 1960s. By deuterating the whole molecule, as opposed to end-labeling, this proposal increased the signal-to-noise ratio of the experiment by several orders of magnitude and made possible for the first time the practical analysis of molecular conformations in bulk polymers. Even so, such experiments could not be undertaken until the completion in Europe of the first instruments employing long wavelength neutrons and large distances between the entrance slit, sample and detector, which allowed deuterium labeling methods to be successfully applied to polymers in the early 1970s.
26
Sarachan, Kathryn L., Joseph E. Curtis e Susan Krueger. "Small-angle scattering contrast calculator for protein and nucleic acid complexes in solution". Journal of Applied Crystallography 46, n. 6 (7 novembre 2013): 1889–93. http://dx.doi.org/10.1107/s0021889813025727.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) with contrast variation can provide useful information about the structure and disposition of two or more chemically distinct components within a complex. TheSASSIE Contrast Calculator(SCC) is a new software tool designed to assist in planning SANS experiments with contrast variation on protein and nucleic acid complexes. On the basis of the primary sequence and deuteration level of each protein or nucleic acid component, theSCCcalculates and plotsI(0), contrast and scattering length densities; since SANS experiments often complement small-angle X-ray scattering studies, the program provides both neutron and X-ray parameters. TheSCCis run as an integrated component ofSASSIE[Curtis, Raghunandan, Nanda & Krueger (2012).Comput. Phys. Commun.183, 382–389], a software suite for atomistic modeling of ensembles of structures consistent with scattering data.
27
Gilles, R., U. Keiderling e A. Wiedenmann. "Silver behenate powder as a possible low-angle calibration standard for small-angle neutron scattering". Journal of Applied Crystallography 31, n. 6 (1 dicembre 1998): 957–59. http://dx.doi.org/10.1107/s0021889898004440.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) is a transmission method working in the angular range 0.4–6° (2θ). In this paper, silver behenate powder [CH3(CH2)20COOAg] (referred to as `AgBE'), one of the very few materials featuring Bragg reflections in the angular range accessible to SANS instruments, is suggested as a possible new SANS wavelength calibration standard. In the past, this powder has been successfully tested as a calibration standard in low-angle X-ray diffraction. Results of new SANS wavelength calibration measurements performed with AgBE and with the traditional method of time-of-flight measurements are presented and compared with low-angle X-ray diffraction measurements.
28
Golub, Maksym, Adrian Kölsch, Artem Feoktystov, Athina Zouni e Jörg Pieper. "Insights into Solution Structures of Photosynthetic Protein Complexes from Small-Angle Scattering Methods". Crystals 11, n. 2 (19 febbraio 2021): 203. http://dx.doi.org/10.3390/cryst11020203.
Testo completoAbstract (sommario):
High-resolution structures of photosynthetic pigment–protein complexes are often determined using crystallography or cryo-electron microscopy (cryo-EM), which are restricted to the use of protein crystals or to low temperatures, respectively. However, functional studies and biotechnological applications of photosystems necessitate the use of proteins isolated in aqueous solution, so that the relevance of high-resolution structures has to be independently verified. In this regard, small-angle neutron and X-ray scattering (SANS and SAXS, respectively) can serve as the missing link because of their capability to provide structural information for proteins in aqueous solution at physiological temperatures. In the present review, we discuss the principles and prototypical applications of SANS and SAXS using the photosynthetic pigment–protein complexes phycocyanin (PC) and Photosystem I (PSI) as model systems for a water-soluble and for a membrane protein, respectively. For example, the solution structure of PSI was studied using SAXS and SANS with contrast matching. A Guinier analysis reveals that PSI in solution is virtually free of aggregation and characterized by a radius of gyration of about 75 Å. The latter value is about 10% larger than expected from the crystal structure. This is corroborated by an ab initio structure reconstitution, which also shows a slight expansion of Photosystem I in buffer solution at room temperature. In part, this may be due to conformational states accessible by thermally activated protein dynamics in solution at physiological temperatures. The size of the detergent belt is derived by comparison with SANS measurements without detergent match, revealing a monolayer of detergent molecules under proper solubilization conditions.
29
Heller, William T. "Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes". Biomolecules 12, n. 11 (29 ottobre 2022): 1591. http://dx.doi.org/10.3390/biom12111591.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
30
Insani, Andon, Arum Patriati, Nadi Suparno, Ratih Langenati, Siriwat Soontaranoon e Ridwan Ridwan. "STUDY OF CERIA STABILIZED ZIRCONIA MICROSPHERES MORPHOLOGY BY SMALL-ANGLE SCATTERING AND MICROSCOPY". Jurnal Sains Materi Indonesia 20, n. 2 (31 gennaio 2019): 89. http://dx.doi.org/10.17146/jsmi.2019.20.2.5474.
Testo completoAbstract (sommario):
STUDY OF CERIA STABILIZED ZIRCONIA MICROSPHERES MORPHOLOGY BY SMALL-ANGLE SCATTERING AND MICROSCOPY. Ceria stabilized zirconia microspheres of about 500 microns were prepared by external gelation. The morphology in nano and micro scale of the microsphere was evaluated. The nanostructure of CSZ microsphere after drying was studied by small angle neutron and x-ray scattering (SANS and SAXS). In this state, the existing of the mixture of ceria oxide and zirconia oxide was observed inside the polymer matrix. The roundness and surface properties of the CSZ microsphere were observed under the optical microscopy (OM) and scanning electron microscopy (SEM). The data showed their good size uniformity, smooth surface, but also the imperfect phase of the gelation.
31
O'Sullivan, T. P., M. E. Vickers e R. K. Heenan. "The characterization of oil-soluble calcium carbonate dispersions using small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS)". Journal of Applied Crystallography 24, n. 5 (1 ottobre 1991): 732–39. http://dx.doi.org/10.1107/s0021889891001309.
Testo completo
32
Murthy, N. Sanjeeva. "Fibrillar Structure and its Relevance to Diffusion, Shrinkage, and Relaxation Processes in Nylon Fibers". Textile Research Journal 67, n. 7 (luglio 1997): 511–20. http://dx.doi.org/10.1177/004051759706700706.
Testo completoAbstract (sommario):
Quantitative prediction of the properties in fibers of semicrystalline polymers requires a detailed description of the fibrillar structure. Use of small-angle x-ray and neutron scattering (saxs and sans) and wide-angle x-ray diffraction (waxd) to obtain such information is illustrated with data from drawn and annealed nylon 6 fibers. The length, diameter, and orientation of the fibrils and the lamellae, and the spacing between the fibrils and the lamellae, are determined using saxs. Diffusion characteristics of the interlamellar and the interfibrillar regions are studied by following the diffusion of solvent molecules (D2O) using sans. Changes in the amorphous orientation are studied by analytically separating the amorphous scattering in waxd patterns into isotropic and anisotropic components. Our data suggest that the glass transition temperature is due to the superposition of relaxations of unoriented and oriented amorphous components. Diffusion is interpreted as occurring through a network of interconnected interfibrillar (voids and mostly oriented amorphous or noncrystalline chain segments) and interlamellar (primarily unoriented amorphous or noncrystalline chain segments) channels. These channels respond differently to drawing and heat setting. The influence of the crystallization of oriented components of the amorphous phase on shrinkage behavior is discussed.
33
Jensen, Grethe Vestergaard, Qing Shi, María J. Hernansanz, Cristiano L. P. Oliveira, G. Roshan Deen, Kristoffer Almdal e Jan Skov Pedersen. "Structure of PEP–PEO block copolymer micelles: exploiting the complementarity of small-angle X-ray scattering and static light scattering". Journal of Applied Crystallography 44, n. 3 (6 maggio 2011): 473–82. http://dx.doi.org/10.1107/s0021889811013343.
Testo completoAbstract (sommario):
The structure of large block copolymer micelles is traditionally determined by small-angle neutron scattering (SANS), covering a large range of scattering vectors and employing contrast variation to determine the overall micelle morphology as well as the internal structure on shorter length scales. The present work shows that the same information can be obtained by combining static light scattering (SLS) and small-angle X-ray scattering (SAXS), which provide information on, respectively, large and short length scales. Micelles of a series of block copolymers of poly(ethylene propylene)-b-poly(ethylene oxide) (PEP–PEO) in a 70% ethanol solution are investigated. The polymers have identical PEP blocks of 5.0 kDa and varying PEO blocks of 2.8–49 kDa. The SLS contrasts of PEP and PEO are similar, providing a homogeneous contrast, making SLS ideal for determining the overall micelle morphology. The SAXS contrasts of the two components are very different, allowing for resolution of the internal micelle structure. A core–shell model with a PEP core and PEO corona is fitted simultaneously to the SAXS and SLS data using the different contrasts of the two blocks for each technique. With increasing PEO molecular weight, a transition from cylindrical to spherical micelles is observed. This transition cannot be identified from the SAXS data alone, but only from the SLS data.
34
Hattendorff, Johannes, Stefan Seidlmayer, Hubert A. Gasteiger e Ralph Gilles. "Li-ion half-cells studied operando during cycling by small-angle neutron scattering". Journal of Applied Crystallography 53, n. 1 (1 febbraio 2020): 210–21. http://dx.doi.org/10.1107/s160057671901714x.
Testo completoAbstract (sommario):
Small-angle neutron scattering (SANS) was recently applied to the in situ and operando study of the charge/discharge process in Li-ion battery full-cells based on a pouch cell design. Here, this work is continued in a half-cell with a graphite electrode cycled versus a metallic lithium counter electrode, in a study conducted on the SANS-1 instrument of the neutron source FRM II at the Heinz Maier-Leibnitz Zentrum in Garching, Germany. It is confirmed that the SANS integrated intensity signal varies as a function of graphite lithiation, and this variation can be explained by changes in the squared difference in scattering length density between graphite and the electrolyte. The scattering contrast change upon graphite lithiation/delithiation calculated from a multi-phase neutron scattering model is in good agreement with the experimentally measured values. Due to the finite coherence length, the observed SANS contrast, which mostly stems from scattering between the (lithiated) graphite and the electrolyte phase, contains local information on the mesoscopic scale, which allows the development of lithiated phases in the graphite to be followed. The shape of the SANS signal curve can be explained by a core–shell model with step-wise (de)lithiation from the surface. Here, for the first time, X-ray diffraction, SANS and theory are combined to give a full picture of graphite lithiation in a half-cell. The goal of this contribution is to confirm the correlation between the integrated SANS data obtained during operando measurements of an Li-ion half-cell and the electrochemical processes of lithiation/delithiation in micro-scaled graphite particles. For a deeper understanding of this correlation, modelling and experimental data for SANS and results from X-ray diffraction were taken into account.
35
Bernardo, Gabriel, Adam L. Washington, Yiwei Zhang, Stephen M. King, Daniel T. W. Toolan, Michael P. Weir, Alan D. F. Dunbar et al. "Does 1,8-diiodooctane affect the aggregation state of PC 71 BM in solution?" Royal Society Open Science 5, n. 9 (settembre 2018): 180937. http://dx.doi.org/10.1098/rsos.180937.
Testo completoAbstract (sommario):
1,8-Diiodooctane (DIO) is an additive used in the processing of organic photovoltaics and has previously been reported, on the basis of small-angle X-ray scattering (SAXS) measurements, to deflocculate nano-aggregates of [6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM) in chlorobenzene. We have critically re-examined this finding in a series of scattering measurements using both X-rays and neutrons. With SAXS, we find that the form of the background solvent scattering is influenced by the presence of DIO, that there is substantial attenuation of the X-rays by the background solvent and that there appears to be beam-induced aggregation. All three factors call into question the suitability of SAXS for measurements on these samples. By contrast, small-angle neutron scattering (SANS) measurements, performed at concentrations of 15 mg ml −1 up to and including 40 mg ml −1 , show no difference in the aggregation state for PC 71 BM in chlorobenzene with and without 3% DIO; we find PC 71 BM to be molecularly dissolved in all solvent cases. In situ film thinning measurements of spin-coated PC 71 BM solution with the DIO additive dry much slower. Optical imaging shows that the fullerene films possess enhanced molecular mobility in the presence of DIO and it is this which, we conclude, improves the nanomorphology and consequently solar cell performance. We propose that any compatible high boiling solvent would be expected to show the same behaviour.
36
Semeraro, Enrico F., Lisa Marx, Johannes Mandl, Moritz P. K. Frewein, Haden L. Scott, Sylvain Prévost, Helmut Bergler, Karl Lohner e Georg Pabst. "Evolution of the analytical scattering model of liveEscherichia coli". Journal of Applied Crystallography 54, n. 2 (3 marzo 2021): 473–85. http://dx.doi.org/10.1107/s1600576721000169.
Testo completoAbstract (sommario):
A previously reported multi-scale model for (ultra-)small-angle X-ray (USAXS/SAXS) and (very) small-angle neutron scattering (VSANS/SANS) of liveEscherichia coliwas revised on the basis of compositional/metabolomic and ultrastructural constraints. The cellular body is modeled, as previously described, by an ellipsoid with multiple shells. However, scattering originating from flagella was replaced by a term accounting for the oligosaccharide cores of the lipopolysaccharide leaflet of the outer membrane including its cross-term with the cellular body. This was mainly motivated by (U)SAXS experiments showing indistinguishable scattering for bacteria in the presence and absence of flagella or fimbrae. The revised model succeeded in fitting USAXS/SAXS and differently contrasted VSANS/SANS data ofE. coliATCC 25922 over four orders of magnitude in length scale. Specifically, this approach provides detailed insight into structural features of the cellular envelope, including the distance of the inner and outer membranes, as well as the scattering length densities of all bacterial compartments. The model was also successfully applied toE. coliK12, used for the authors' original modeling, as well as for two otherE. colistrains. Significant differences were detected between the different strains in terms of bacterial size, intermembrane distance and its positional fluctuations. These findings corroborate the general applicability of the approach outlined here to quantitatively study the effect of bactericidal compounds on ultrastructural features of Gram-negative bacteria without the need to resort to any invasive staining or labeling agents.
37
Konarev, Petr V., e Dmitri I. Svergun. "A posterioridetermination of the useful data range for small-angle scattering experiments on dilute monodisperse systems". IUCrJ 2, n. 3 (21 aprile 2015): 352–60. http://dx.doi.org/10.1107/s2052252515005163.
Testo completoAbstract (sommario):
Small-angle X-ray and neutron scattering (SAXS and SANS) experiments on solutions provide rapidly decaying scattering curves, often with a poor signal-to-noise ratio, especially at higher angles. On modern instruments, the noise is partially compensated for by oversampling, thanks to the fact that the angular increment in the data is small compared with that needed to describe adequately the local behaviour and features of the scattering curve. Given a (noisy) experimental data set, an important question arises as to which part of the data still contains useful information and should be taken into account for the interpretation and model building. Here, it is demonstrated that, for monodisperse systems, the useful experimental data range is defined by the number of meaningful Shannon channels that can be determined from the data set. An algorithm to determine this number and thus the data range is developed, and it is tested on a number of simulated data sets with various noise levels and with different degrees of oversampling, corresponding to typical SAXS/SANS experiments. The method is implemented in a computer program and examples of its application to analyse the experimental data recorded under various conditions are presented. The program can be employed to discard experimental data containing no useful information in automated pipelines, in modelling procedures, and for data deposition or publication. The software is freely accessible to academic users.
38
Almásy, László, Ana-Maria Putz, Adél Len, Josef Plestil e Cecilia Savii. "Small-angle scattering investigation of silica xerogels and sonogels prepared with ionic liquid pyridinium tetrafluoroborate". Processing and Application of Ceramics 11, n. 3 (2017): 229–33. http://dx.doi.org/10.2298/pac1703229a.
Testo completoAbstract (sommario):
Silica matrices were prepared via acid catalysed sol-gel processing augmented with sonocatalysis. As silica precursors, a mixture of tetra-functionalized alkoxide (TMOS) and three-functionalized alkoxide methyl-trimethoxysilane (MTMS) were employed. Ionic liquid N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]), was used in various proportions, aiming to catalyse the sol-gel reactions, and to influence the mesoporous silica materials properties, serving as pore template. Small-angle neutron (SANS) and small-angle X-ray scattering (SAXS) techniques were used to explore the xerogels and sonogels microstructure evolution as a function of the IL/Si molar ratio. The results show a strong increase of the primary particle size under the influence of the ionic liquid. Ultrasonic agitation leads to further size increase by ca. 10%.
39
Dargel, Carina, Friederike Gräbitz-Bräuer, Ramsia Geisler, Pascal Fandrich, Yvonne Hannappel, Lionel Porcar e Thomas Hellweg. "Stable DOPG/Glycyrrhizin Vesicles with a Wide Range of Mixing Ratios: Structure and Stability as Seen by Scattering Experiments and Cryo-TEM". Molecules 26, n. 16 (16 agosto 2021): 4959. http://dx.doi.org/10.3390/molecules26164959.
Testo completoAbstract (sommario):
Phosphatidylglycerols represent a large share of the lipids in the plasmamembrane of procaryotes. Therefore, this study investigates the role of charged lipids in the plasma membrane with respect to the interaction of the antiviral saponin glycyrrhizin with such membranes. Glycyrrhizin is a natural triterpenic-based surfactant found in licorice. Vesicles made of 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1’-glycerol) (DOPG)/glycyrrhizin are characterized by small-angle scattering with neutrons and X-rays (SANS and SAXS). Small-angle scattering data are first evaluated by the model-independent modified Kratky–Porod method and afterwards fitted by a model describing the shape of small unilamellar vesicles (SUV) with an internal head-tail contrast. Complete miscibility of DOPG and glycyrrhizin was revealed even at a ratio of lipid:saponin of 1:1. Additional information about the chain-chain correlation distance of the lipid/saponin mixtures in the SUV structures is obtained from wide-angle X-ray scattering (WAXS).
40
Drescher, Simon, Vasil M. Garamus, Christopher J. Garvey, Annette Meister e Alfred Blume. "Aggregation behaviour of a single-chain, phenylene-modified bolalipid and its miscibility with classical phospholipids". Beilstein Journal of Organic Chemistry 13 (23 maggio 2017): 995–1007. http://dx.doi.org/10.3762/bjoc.13.99.
Testo completoAbstract (sommario):
In the present work, we describe the synthesis of a single-chain, phenylene-modified bolalipid with two phosphocholine headgroups, PC-C18pPhC18-PC, using a Sonogashira cross-coupling reaction as a key step. The aggregation behaviour was studied as a function of temperature using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and small angle neutron scattering (SANS). We show that our new bolalipid self-assembles into nanofibres, which transform into flexible nanofibres at 27 °C and further to small elongated micelles at 45 °C. Furthermore, the miscibility of the bolalipid with bilayer-forming phosphatidylcholines (DMPC, DPPC, and DSPC) was investigated by means of DSC, TEM, FTIR, and small angle X-ray scattering (SAXS). We could show that the PC-C18pPhC18-PC is partially miscible with saturated phosphatidylcholines; however, closed lipid vesicles with an increased thermal stability were not found. Instead, bilayer fragments and disk-like aggregates are formed.
41
Loy, Chee Wah, Khamirul Amin Matori, Norhazlin Zainuddin, Andrew E. Whitten, Liliana de Campo, Nur Izzah Md Nasir, Nur Fadilah Baharuddin Pallan, Mohd Hafiz Mohd Zaid, Nadakkavil Alassan Zarifah e Siegbert Schmid. "Small Angle Neutron Scattering Study of a Gehlenite-Based Ceramic Fabricated from Industrial Waste". Solid State Phenomena 290 (aprile 2019): 22–28. http://dx.doi.org/10.4028/www.scientific.net/ssp.290.22.
Testo completoAbstract (sommario):
This paper presents a small angle neutron scattering (SANS) study of a novel porous gehlenite-based ceramic, synthesised from a homogeneous powder mixture of soda-lime-silicate (SLS) glass, α-alumina, calcite and calcium fluoride via solid-state sintering at 1200 °C. The products of sintering at single temperatures from 600 to 1200 °C are examined by X-ray diffraction (XRD). Sintering of the mixture below 1200 °C forms two intermediate phases (Na2CaSi3O8 and Ca4Si2O7F2). Nepheline and α-alumina are minor phases in the gehlenite-based ceramic fabricated through sintering at 1200 °C. The microstructure of the gehlenite-based ceramic is investigated using field-emission scanning electron microscopy (FESEM) and SANS at the Australian Centre for Neutron Scattering. This study also evaluated the specific surface area of the gehlenite-based ceramic (~3.0 m2 cm–3) from quantitative analysis of SANS data.
42
Schmiele, Martin, Simone Gehrer e Tobias Unruh. "Small-angle scattering simulations for suspensions of nanocrystals". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C597. http://dx.doi.org/10.1107/s2053273314094029.
Testo completoAbstract (sommario):
Suspensions of nanocrystals which possess large lattice spacings d(hkl) and only a small number of unit cells along the direction of the reciprocal lattice vector G(hkl) can feature broadened Bragg peaks in small-angle scattering (SAS) patterns. The scattering from molecules located at the interface between the nanocrystals and the dispersion medium which stabilize and functionalize the nanocrystals can interfere with the scattering of the nanocrystals and affect the shape and position of their Bragg peaks. This allows to study how these molecules arrange on the surface of the nanocyrstals. As an example we study suspensions of lecithin stabilized β-tripalmitin nanocrystals which adopt a platelet-like shape. Their SAS patterns exhibit a broadened 001 Bragg peak (cf. SAXS curves in the graphical abstract). With the x-ray and neutron powder pattern simulation analysis (XNPPSA) we have demonstrated that the SAXS and SANS patterns of dilute tripalmitin (3 wt%) suspensions can be simultaneously reproduced on an absolute scale [1,2]. Thereby, powder averaged SAS diffractograms are computed for an ensemble of nanocrystals which are embedded in a dispersion medium. The crystallographic structure of the nanocrystals (CIF-file) and their geometry are taken into account and the amphiphilic lecithin molecules which cover the nanocrystals are modelled with two shells (cf. model in the right inset). From the analysis of the fitted shell thicknesses and scattering length densities it turns out that the lecithin molecules arrange rather flatly and densely packed on the surface of the nanocyrstals. Moreover, the XNPPSA method allows a reliable determination of the thickness distribution of the nanocrystals with molecular resolution [1,2]. With rising tripalmitin concentration the platelets form self-assembled stack-like structures [1,3] and finally nematic liquid-crystalline domains. The XNPPSA allows to investigate the structure and amount of such stacks in the suspensions.
43
Nabiyev, Asif A., Andrzej Olejniczak, Akhmed Kh Islamov, Andrzej Pawlukojc, Oleksandr I. Ivankov, Maria Balasoiu, Alexander Zhigunov et al. "Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects". Nanomaterials 11, n. 10 (11 ottobre 2021): 2673. http://dx.doi.org/10.3390/nano11102673.
Testo completoAbstract (sommario):
Herein, we investigated the influence of two types of nanoparticle fillers, i.e., amorphous SiO2 and crystalline ZrO2, on the structural properties of their nanocomposites with high-density polyethylene (HDPE). The composite films were prepared by melt-blending with a filler content that varied from 1% to 20% v/v. The composites were characterized by small- and wide-angle x-ray scattering (SAXS and WAXS), small-angle neutron scattering (SANS), Raman spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). For both fillers, the nanoaggregates were evenly distributed in the polymer matrix and their initial state in the powders determined their surface roughness and fractal character. In the case of the nano-ZrO2 filler, the lamellar thickness and crystallinity degree remain unchanged over a broad range of filler concentrations. SANS and SEM investigation showed poor interfacial adhesion and the presence of voids in the interfacial region. Temperature-programmed SANS investigations showed that at elevated temperatures, these voids become filled due to the flipping motions of polymer chains. The effect was accompanied by a partial aggregation of the filler. For nano-SiO2 filler, the lamellar thickness and the degree of crystallinity increased with increasing the filler loading. SAXS measurements show that the ordering of the lamellae is disrupted even at a filler content of only a few percent. SEM images confirmed good interfacial adhesion and integrity of the SiO2/HDPE composite. This markedly different impact of both fillers on the composite structure is discussed in terms of nanoparticle surface properties and their affinity to the HDPE matrix.
44
Vergnat, Virginie, Benoît Heinrich, Michel Rawiso, René Muller, Geneviève Pourroy e Patrick Masson. "Iron Oxide/Polymer Core–Shell Nanomaterials with Star-like Behavior". Nanomaterials 11, n. 9 (21 settembre 2021): 2453. http://dx.doi.org/10.3390/nano11092453.
Testo completoAbstract (sommario):
Embedding nanoparticles (NPs) with organic shells is a way to control their aggregation behavior. Using polymers allows reaching relatively high shell thicknesses but suffers from the difficulty of obtaining regular hybrid objects at gram scale. Here, we describe a three-step synthesis in which multi-gram NP batches are first obtained by thermal decomposition, prior to their covalent grafting by an atom transfer radical polymerization (ATRP) initiator and to the controlled growing of the polymer shell. Specifically, non-aggregated iron oxide NPs with a core principally composed of γ-Fe2O3 (maghemite) and either polystyrene (PS) or polymethyl methacrylate (PMMA) shell were elaborated. The oxide cores of about 13 nm diameter were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). After the polymerization, the overall diameter reached 60 nm, as shown by small-angle neutron scattering (SANS). The behavior in solution as well as rheological properties in the molten state of the polymeric shell resemble those of star polymers. Strategies to further improve the screening of NP cores with the polymer shells are discussed.
45
Bugrov, Alexander N., Yulia E. Gorshkova, Elena M. Ivan’kova, Gennady P. Kopitsa, Alina A. Pavlova, Elena N. Popova, Valentina E. Smirnova et al. "Domain Structure, Thermal and Mechanical Properties of Polycaprolactone-Based Multiblock Polyurethane-Ureas under Control of Hard and Soft Segment Lengths". Polymers 14, n. 19 (3 ottobre 2022): 4145. http://dx.doi.org/10.3390/polym14194145.
Testo completoAbstract (sommario):
A series of multiblock polyurethane-ureas (PUU) based on polycaprolactone diol (PCL) with a molecular mass of 530 or 2000 g/mol, as well as hard segments of different lengths and structures, were synthesized by the step-growth polymerization method. The chemical structure of the synthesized multiblock copolymers was confirmed by IR- and NMR-spectroscopy. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to determine the relaxation and phase transition temperatures for the entire series of the obtained PUU. The X-ray diffraction (XRD) method made it possible to identify PUU compositions in which the crystallizability of soft segments (SS) is manifested due to their sufficient length for self-organization and structuring. Visualization of the crystal structure and disordering of the stacking of SS with an increase in their molecular mobility during heating are shown using optical microscopy. The change in the size of the hard phase domains and the value of the interdomain distance depending on the PCL molecular mass, as well as the length and structure of the hard block in the synthesized PUU, were analyzed using small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS). The evolution of the domain structure upon passing through the melting and crystallization temperatures of PUU soft blocks was studied using SANS. The studies carried out made it possible to reveal the main correlations between the chemical structure of the synthesized PUU and their supramolecular organization as well as thermal and mechanical properties.
46
Hardman-Rhyne, K. A., e N. F. Berk. "Characterization of alumina powder using multiple small-angle neutron scattering. II. Experiment". Journal of Applied Crystallography 18, n. 6 (1 dicembre 1985): 473–79. http://dx.doi.org/10.1107/s0021889885010731.
Testo completoAbstract (sommario):
Small-angle neutron scattering techniques developed in the preceding paper [Berk & Hardman-Rhyne (1985). J. Appl. Cryst. 18, 467–472] are used to obtain microstructural parameters of high-purity alumina powder. The values of the particle size, volume fraction and surface area have been obtained and are compared to data from techniques such as laser light scattering, X-ray sedigraph and scanning electron microscopy. The particles exhibit a log–normal distribution and are spherical in shape with a mean particle size of 342 nm determined from SANS analyses of both beam broadening and Porod regions.
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Putz, Ana-Maria, Mihaela Ciopec, Adina Negrea, Oana Grad, Cătălin Ianăşi, Oleksandr I. Ivankov, Marija Milanović, Ivan Stijepović e László Almásy. "Comparison of Structure and Adsorption Properties of Mesoporous Silica Functionalized with Aminopropyl Groups by the Co-Condensation and the Post Grafting Methods". Materials 14, n. 3 (29 gennaio 2021): 628. http://dx.doi.org/10.3390/ma14030628.
Testo completoAbstract (sommario):
The adsorptive potential has been evaluated for the aminopropyl functionalized mesoporous silica materials obtained by co-condensation and post grafting methods. Nitrogen sorption, small angle neutron and X-ray scattering (SANS and SAXS) demonstrated high surface area and well-ordered hexagonal pore structure suitable for applications as adsorbents of metals from waste waters. A comparison of Cr(VI) adsorption properties of the materials prepared by different functionalization methods has been performed. The obtained results demonstrated the adsorption capacity due to the affinity of the chromium ions to the amino groups, and showed that co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTES) resulted in higher metal sorption capacity of the materials compared to post-synthesis grafting of aminopropyl groups onto the mesoporous silica particles.
48
Tu, Shuyang, Haijiao Zhang, Yawen Li, Yongchao Zhang, Qiang Tian, László Almásy, Xianhui Xu, Rongguang Zhang, Aihua Zou e Na Li. "Effect of Shiga Toxin on Inhomogeneous Biological Membrane Structure Determined by Small-Angle Scattering". Applied Sciences 11, n. 15 (28 luglio 2021): 6965. http://dx.doi.org/10.3390/app11156965.
Testo completoAbstract (sommario):
Inhomogeneous structure occurring in biological membranes being rich in glycosphingolipids (GSL) has been proposed as an important phenomenon involved in the cellular endocytosis process. However, little is known about the correlation between the formation of microdomains and the GSL-dependent biogenesis for tubular endocytic pits occurred on the surface of the cellular membrane. In the present work, the interaction between the bacterial Shiga toxin from Escherichia coli (STxB) and its cellular receptor GSL globotriaosylceramide (Gb3) were studied using small unilamellar vesicle (SUV). The model membrane invagination induced by STxB was determined by the contrast variation small-angle neutron scattering (SANS) and the synchrotron radiation facility based small-angle X-ray scattering (SR-SAXS). The results revealed that Gb3 molecules provided the binding sites for STxB, inducing increased membrane fluctuation. The formation of protein–lipid complex (STxB-Gb3) apparently induced the thinning of model membrane with the thickness decreased from 3.10 nm to 2.50 nm. It is the first time to successfully characterize the mesoscopic change on membrane thickness upon GSL-dependent endocytic process using a small-angle scattering technique. Overall, this paper provided a practical method to quantify the inhomogeneous biological membrane structures, which is important to understand the cellular endocytosis process.
49
Keshavarzi, Atoosa, Ali Asi Shirazi, Rastislav Korfanta, Nina Královič, Mária Klacsová, Juan Carlos Martínez, José Teixeira, Sophie Combet e Daniela Uhríková. "Thermodynamic and Structural Study of Budesonide—Exogenous Lung Surfactant System". International Journal of Molecular Sciences 25, n. 5 (4 marzo 2024): 2990. http://dx.doi.org/10.3390/ijms25052990.
Testo completoAbstract (sommario):
The clinical benefits of using exogenous pulmonary surfactant (EPS) as a carrier of budesonide (BUD), a non-halogenated corticosteroid with a broad anti-inflammatory effect, have been established. Using various experimental techniques (differential scanning calorimetry DSC, small- and wide- angle X-ray scattering SAXS/WAXS, small- angle neutron scattering SANS, fluorescence spectroscopy, dynamic light scattering DLS, and zeta potential), we investigated the effect of BUD on the thermodynamics and structure of the clinically used EPS, Curosurf®. We show that BUD facilitates the Curosurf® phase transition from the gel to the fluid state, resulting in a decrease in the temperature of the main phase transition (Tm) and enthalpy (ΔH). The morphology of the Curosurf® dispersion is maintained for BUD < 10 wt% of the Curosurf® mass; BUD slightly increases the repeat distance d of the fluid lamellar phase in multilamellar vesicles (MLVs) resulting from the thickening of the lipid bilayer. The bilayer thickening (~0.23 nm) was derived from SANS data. The presence of ~2 mmol/L of Ca2+ maintains the effect and structure of the MLVs. The changes in the lateral pressure of the Curosurf® bilayer revealed that the intercalated BUD between the acyl chains of the surfactant’s lipid molecules resides deeper in the hydrophobic region when its content exceeds ~6 wt%. Our studies support the concept of a combined therapy utilising budesonide—enriched Curosurf®.
50
Schmidt-Rohr, Klaus. "Simulation of small-angle scattering curves by numerical Fourier transformation". Journal of Applied Crystallography 40, n. 1 (12 gennaio 2007): 16–25. http://dx.doi.org/10.1107/s002188980604550x.
Testo completoAbstract (sommario):
A simple numerical approach for calculating theq-dependence of the scattering intensity in small-angle X-ray or neutron scattering (SAXS/SANS) is discussed. For a user-defined scattering density on a lattice, the scattering intensityI(q) (qis the modulus of the scattering vector) is calculated by three-dimensional (or two-dimensional) numerical Fourier transformation and spherical summation inqspace, with a simple smoothing algorithm. An exact and simple correction for continuous rather than discrete (lattice-point) scattering density is described. Applications to relatively densely packed particles in solids (e.g.nanocomposites) are shown, where correlation effects make single-particle (pure form-factor) calculations invalid. The algorithm can be applied to particles of any shape that can be defined on the chosen cubic lattice and with any size distribution, while those features pose difficulties to a traditional treatment in terms of form and structure factors. For particles of identical but potentially complex shapes, numerical calculation of the form factor is described. Long parallel rods and platelets of various cross-section shapes are particularly convenient to treat, since the calculation is reduced to two dimensions. The method is used to demonstrate that the scattering intensity from `randomly' parallel-packed long cylinders is not described by simple 1/qand 1/q4power laws, but at cylinder volume fractions of more than ∼25% includes a correlation peak. The simulations highlight that the traditional evaluation of the peak position overestimates the cylinder thickness by a factor of ∼1.5. It is also shown that a mix of various relatively densely packed long boards can produceI(q) ≃ 1/q, usually observed for rod-shaped particles, without a correlation peak.