The basics of small-angle neutron scattering (SANS for new users of structural biology)

Jeffries, Cy M.; Pietras, Zuzanna; Svergun, Dmitri I.

doi:10.1051/epjconf/202023603001

Cited by 7 publications

(5 citation statements)

References 57 publications

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“…From which we can draw a geometric comparison, where the scattering cross section forms a circle with a radius b. The larger the scattering length, the larger the circle and the higher the probability of a scattering event [28]. Indeed, one interpretation of the scattering cross-section is the effective interaction area for the neutron [29], in a sense it therefore describes the effective size of the nucleus for the neutron.…”

Section: The Scattering Cross Sectionmentioning

confidence: 99%

Multilayer neutron optics based on isotope-enriched 11B4C

Stendahl

2023

Linköping Studies in Science and Technology. Dissertations

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The work in this thesis covers the design, growth and characterisation of neutron multilayers. The achieved reflectivity performance of a neutron multilayer depends on the achieved optical contrast between the layers as well as the achieved interface width between the layers. Because the reflectivity of a neutron multilayer depends exponentially on the square of the interface width, even a modest improvement can substantially increase the achieved reflectivity performance. It is for this reason that a large part of this work has been focused on growing smoother and more abrupt interfaces in neutron multilayers. As multilayers are such an integral component of most neutron optical instruments, any improvement in terms of reflectivity performance has broad implications for all conducted neutron scattering experiments. The conventional material system of choice for neutron optical components is Ni/Ti, owing to the high contrast in scattering length density (SLD). The reflected intensity of such components is largely dependent on the interface width, primarily caused by the formation of nanocrystallites, interdiffusion, and/or intermixing. Apart from hampering the reflectivity performance, the finite interface width between the layers also limits the minimum usable layer thickness in the mirror stack. In this work, Ni/Ti based multilayers are grown using ion-assisted magnetron sputtering. By co-depositing B 4 C in the multilayer stack, the formation of nanocrystallites as well as intermetallics between the interfaces were succesfully prevented. The co-deposition of B 4 C has been combined with a modulated ion assistance scheme, where an initial buffer layer is grown at a low ion energy creating abrupt interfaces, while the remainder of the layer is grown at a higher ion energy, smoothening the interfaces. X-ray reflectivity (XRR) measurements show significant improvements in terms of reflectivity when the multilayers are co-deposited with B 4 C . This has further been investigated using low neutron-absorbing isotope-enriched 11 B 4 C . The deposited 11 B 4 C containing multilayers have been characterized using neutron reflectometry, X-ray reflectivity, transmission electron microscopy (TEM), elastic recoil detection analysis (ERDA), X-ray photoelectron spectroscopy (XPS) and grazing incidence small angle scattering (GISAXS). Structural characteristics in the growth direction of the multilayer such as interface width and thickness variations have been determined by combined fits on X-ray and neutron reflectivity measurements, while the interface morphology has been investigated using GISAXS. The coupled fits to specular X-ray and neutron reflectivity measurements suggest a significant improvement in interface width for the samples that have been co-deposited with 11 B 4 C using a modulated on assistance scheme during deposition, where an interface width of 2.7 Å has been i Abstract achieved in a 11 B 4 C containing multilayer. The GISAXS measurements show that the co-deposition of 11 B 4 C leads to mounded interfaces ...

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Section: The Scattering Cross Sectionmentioning

confidence: 99%

Multilayer neutron optics based on isotope-enriched 11B4C

Stendahl

2023

Linköping Studies in Science and Technology. Dissertations

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“…Several recent reviews provide a good overview of the use of SANS in biophysics. 96 − 101 However, even though SANS has been used in many studies of lipid vesicles, there are none—to the best of our knowledge—on the absorption of ILs, making our present study the first SANS investigation of this kind.…”

Section: Introductionmentioning

confidence: 99%

“…SANS is a widely used neutron scattering technique to determine nanoscale structures. − Its basic principles are very similar to those of small-angle X-ray scattering (SAXS); however, their ability to resolve structures differs, making them two complementary techniques. − SANS has been successfully used to study lipid vesicles in different environments and conditions as, for example, to determine (i) the effect of temperature, pressure, and pH on the phase behavior of (DMPC) lipid vesicles; ,− (ii) the degree of asymmetry and domain formation in mixed lipid vesicles; − (iii) the absorption of antimicrobial peptides and drugs in lipid vesicles; − and (iv) the structure of lipid-based drug-delivery carriers. Several recent reviews provide a good overview of the use of SANS in biophysics. − However, even though SANS has been used in many studies of lipid vesicles, there are noneto the best of our knowledgeon the absorption of ILs, making our present study the first SANS investigation of this kind.…”

Section: Introductionmentioning

confidence: 99%

Absorption of the [bmim][Cl] Ionic Liquid in DMPC Lipid Bilayers across Their Gel, Ripple, and Fluid Phases

Benedetto

Kelley

2022

J. Phys. Chem. B

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Lipid bilayers are a key component of cell membranes and play a crucial role in life and in bio-nanotechnology. As a result, controlling their physicochemical properties holds the promise of effective therapeutic strategies. Ionic liquids (ILs)—a vast class of complex organic electrolytes—have shown a high degree of affinity with lipid bilayers and can be exploited in this context. However, the chemical physics of IL absorption and partitioning into lipid bilayers is yet to be fully understood. This work focuses on the absorption of the model IL [bmim][Cl] into 1,2-dimyristoyl- sn -glycero-3-phosphocholine (DMPC) lipid bilayers across their gel, ripple, and fluid phases. Here, by small-angle neutron scattering, we show that (i) the IL cations are absorbed in the lipid bilayer in all its thermodynamic phases and (ii) the amount of IL inserted into the lipid phase increased with increasing temperature, changing from three to four IL cations per 10 lipids with increasing temperature from 10 °C in the gel phase to 40 °C in the liquid phase, respectively. An explicative hypothesis, based on the entropy gain coming from the IL hydration water, is presented to explain the observed temperature trend. The ability to control IL absorption with temperature can be used as a handle to tune the effect of ILs on biomembranes and can be exploited in bio-nanotechnological applications.

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“…and thereby provides an opportunity to assess the redistribution of mass during the new arrangement of components (Jeffries et al, 2020). The SANS method has been extensively employed in the realm of structured polymers and proteins (Cousin et al, 2005;Liu et al, 2009;Hong et al, 2012), e.g., in analyzing the conformational alterations when higher-order assemblies are forged of macromolecules (Arrighi et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Small angle neutron scattering studies of shale oil occurrence status at nanopores

Zhang,

Hu,

Tian

et al. 2024

Adv. Geo-Energy Res.

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Utilizing small angle neutron scattering techniques on organic shales, this study presents an innovative approach for characterizing the status of oil occurrence, and new insights into pore scale assessment through scattering vector-pore size relationship. The results indicate the successful identification of different shale oil occurrence status, before and after solvent extraction of residual oil for four shale samples with different contents of total organic carbon. In addition, coupled with density distribution analyses, the work demonstrates that shale samples with lower total organic carbon contents typically signify a smaller radius of gyration with better oil mobility, which indicates a greater wave oscillation with a larger pore size to be estimated from the scattering vector. This work also elucidates the notable scenarios of an increasing pore size could correspond to a decreasing radius of gyration caused by mass density redistribution. For polydisperse systems, this research illustrates the variations in pore volumetric ratio impact the scattering intensity, whereas pore scale changes affect the oscillation pattern. This novel research of analyzing mass density distribution and pore scale information in real space is also suitable for other porous media systems.

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The basics of small-angle neutron scattering (SANS for new users of structural biology)

Cited by 7 publications

References 57 publications

Multilayer neutron optics based on isotope-enriched 11B4C

Multilayer neutron optics based on isotope-enriched 11B4C

Absorption of the [bmim][Cl] Ionic Liquid in DMPC Lipid Bilayers across Their Gel, Ripple, and Fluid Phases

Small angle neutron scattering studies of shale oil occurrence status at nanopores

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