Search Results (216)

Polarized Small-Angle Neutron Scattering is a versatile low-energy neutron scattering technique that allows for the access of magnetic information on nanosize objects of size 2–100 nm, from individual properties like the magnetization distribution inside the object to the collective behaviors, e.g., spin-glass effects or long-range magnetic ordering. The multi-scale possibilities of this technique is particularly relevant to encompass simultaneously the individual and collective many-body phenomena. In this article, we report the direct measurement of the magnetic form factor of “Prussian Blue Analog” molecular-based Ferromagnetic nanoparticles ${\mathrm{Cs}}_{\mathrm{x}}^{\mathrm{I}}{\mathrm{Ni}}^{\mathrm{II}}\left[{\mathrm{Cr}}^{\mathrm{III}}{\left(\mathrm{CN}\right)}_6\right]$ embedded in a polymer matrix with use of Polarized Small-Angle Neutron Scattering. We show that PSANS is particularly adapted to evaluate the internal magnetization distribution in nanoparticles and determine their magnetic morphology. Full article

This study developed a neutron-beam-focusing supermirror for grazing-incidence small-angle neutron scattering (GISANS) measurements. We adopted point-to-point beam focusing based on an ellipse whose two foci correspond to a virtual point source and a spot on the detector surface. The focusing supermirror was fabricated by depositing NiC/Ti supermirror film with ion-beam sputtering on a precise elliptic surface of fused quartz figured using the elastic emission machining technique. Neutron measurements at the pulsed neutron reflectometer BL17 of the MLF, J-PARC, successfully demonstrated that the focusing supermirror enhances the beam intensity twentyfold compared with an optimally collimated beam, achieving a signal-to-background ratio of the focal spot as high as 500. The mirror can be readily installed and used at BL17 for time-of-flight GISANS measurements. Full article

The elliptical cylindrical mirror has been utilized in neutron small-angle scattering and reflectometry to enhance the neutron intensity at the sample position. However, the performance of the elliptical cylindrical mirror can be impacted by surface slope errors, reflectivity, and misalignments. In this work, the performance of the elliptical cylindrical mirror under different error conditions has been analyzed comprehensively, and a 250-mm-long elliptical cylindrical mirror was designed and developed. The simulations show that a source size below 1 mm is required to achieve a peak gain above 6, with a theoretical peak gain of 16× with a 0.1 mm source. The rotational misalignment of 0.03° around the Y-axis can decrease gain from 16× to 6×. The designed mirror was fabricated with a surface figure error of 110 nm (RMS), and a roughness below 0.5 nm (RMS), and was coated with an m = 4 supermirror. The mirror was aligned and tested in the dedicated neutron beamline of the Chinese mianyang research reactor, and the results show a peak gain of 12.77 with a 0.1 mm slit source. Full article

Poloxamer-based drug delivery systems are widely used in the pharmaceutical sector. The structural characterization of these systems is crucial for the development of new drug delivery systems and for the optimization of their properties. In this study, we utilized small-angle neutron scattering (SANS) to investigate the structures of poloxamer-based drug delivery systems. The samples were measured using the SANS technique on the VSANS-V16 instrument at Helmholtz-Zentrum Berlin (HZB), Germany. The samples contained 20% poloxamer (P407) and 0.2% of a drug (ibuprofen, ketoprofen, diclofenac) in deuterated water (D₂O) for SANS. The samples varied in terms of temperature analysis (25 °C, common storage temperature; 37 °C, human body temperature; 40 °C, fever temperature). The data analysis involved modeling the data using a Python-based routine. The model used consisted of an isotropic solution of polydisperse spherical micelles. The intensity as a function of the scattering vector was modeled as the product of the form factor and the interparticle structure factor, with the latter described within the local monodisperse approximation regime. Additionally, a scattering contribution was observed, which was associated with the presence of crystalline superstructures formed by micelles that organized into a cubic structure. The data analysis provided important information about the system, such as the average radius, the size distribution, and the thickness of the layer surrounding the micellar core. The results will contribute to the development and optimization of new drug delivery systems that are more effective and safer for medical applications. Full article

Herein we describe the development of the first model amphiphilic polymer conetwork (APCN) comprising a short hydrophobic hexa(L-alanine) segment being the outer block of an amphiphilic four-armed star block copolymer with inner poly(ethylene glycol) (PEG) blocks bearing benzaldehyde terminal groups and end-linked with another four-armed star PEG homopolymer (tetraPEG star) bearing aryl-substituted acylhydrazide terminal groups. The present successful synthesis that yielded the peptide-containing model APCN was preceded by several unsuccessful efforts that followed different synthetic strategies. In addition to the synthetic work, we also present the structural characterization of the peptide-bearing APCN in D₂O using small-angle neutron scattering (SANS). Full article

The bacterium Bacillus anthracis secretes three protein exotoxins: Protective Antigen 83 (PA83), Lethal Factor (LF), and Edema Factor (EF). A cleaved form of PA83 (PA63) aids LF and EF entry into the cytoplasm, which leads to anthrax-induced cell death. The Protein Data Bank (PDB) has more than 25 structures of LF: the monomer alone, bound with inhibitors, or bound to PA63. The structures are all—with only minor shifts of a few Ångströms—nearly congruent. We have measured the structure of LF at equilibrium in D₂O solution by small-angle neutron scattering (SANS). The shape is modeled well by a parallelepiped (all angles 90°) with dimensions of 12 Å × 49 Å × 129 Å. For a protein with a typical density of 1.4, the molecular weight would be between 55 and 94 kDa, which is comparable to that of the 90.2 kDa monomer. However, the LF crystal structure PDB 1pwu (a generally V-shaped molecule with equal arm lengths ≈ 70 Å) with the same model fits the dimensions 30 Å × 48 Å × 104 Å. Given the large changes in the long and short dimensions, straightforward physical modeling of the solution structure from the crystal form is unable to match the SANS results. Full article

Granular samples are often used to characterize the pore structure of shale. To systematically analyze the influence of particle size on pore characteristics, case studies were performed on two groups of organic-rich deep shale samples. Multiple methods, including small-angle neutron scattering (SANS), low-pressure nitrogen gas adsorption (LP-N₂GA), low-pressure carbon dioxide gas adsorption (LP-CO₂GA), and XRD analysis, were adopted to investigate how the crushing process would affect pore structure parameters and the fractal features of deep shale samples. The research indicates that with the decrease in particle size, the measurements from nitrogen adsorption and SANS experiments significantly increase, with relative effects reaching 95.09% and 51.27%, respectively. However, the impact on carbon dioxide adsorption measurements is minor, with a maximum of only 8.97%. This suggests that the comminution process primarily alters the macropore structure, with limited influence on the micropores. Since micropores contribute the majority of the specific surface area in deep shale, the effect of particle size variation on the specific surface area is negligible, averaging only 16.52%. Shales exhibit dual-fractal characteristics. The distribution range of the mass fractal dimension of the experimental samples is 2.658–2.961, which increases as the particle size decreases. The distribution range of the surface fractal dimension is 2.777–2.834, which decreases with the decrease in particle size. Full article

Soft matter and biological materials are characterized by a complex morphology consisting of multiple structural levels that are either hierarchically organized or coexist over a length scale from a few Å up to the size of µm. For a structural characterization of such morphologies, an extended Q-range must be covered in X-ray and neutron scattering experiments. Neutrons offer the unique advantage of contrast variation and matching by D-labeling, which is of great value for the characterization of hydrocarbon systems, which are essentially the constituents of soft matter and biological materials. The combination of ultra- and small-angle neutron scattering techniques (USANS and SANS) on complementary beamlines has long been used for such experimental investigations. However, the combined use of USANS and SANS methods at the same beamline for simultaneous acquisition of scattering data over a wide Q-range is necessary when working with sensitive or expensive samples that require special preparation or in situ treatment during the structural characterization. For this reason, several pinhole SANS instruments have been equipped with focusing lenses to allow additional measurements at lower Q values, in the USANS range. The use of neutron lenses has the additional advantage of enhancing the intensity on the sample by providing the ability to work with larger samples while maintaining the same resolution as in pinhole mode. The experimental approach for using neutron lenses to enhance the intensity and extend the Q-range to lower values than in pinhole mode is presented using examples from studies on the pinhole SANS diffractometers equipped with focusing lenses. Full article

Mesoporous silica sieves have been prepared through sol–gel synthesis using diester gemini surfactants as pore templates, aiming to obtain new materials with potential use for water remediation. A series of mesoporous spherical silica particles of submicron size have been prepared in an alkali-catalyzed reaction, using a tetraethyl orthosilicate precursor and bis-quaternary ammonium gemini surfactants with diester spacers of varied lengths as pore-forming agents. The effect of the spacer length on the particle morphology was studied using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, scanning, and transmission electron microscopy (SEM, TEM). The results revealed that for all spacer lengths, a long-range hexagonal pore ordering developed in the materials. The silica particles were nearly spherical, with sizes below 1 micrometer, and a weak dependence of the mean particle size on the spacer length could be observed. The template removal procedure had a strong influence on the porosity: calcination caused a moderate shrinkage of the pores while retaining the hexagonal structure, whereas treatment with acidified ethanol resulted in only partial removal of the surfactants; however, the hexagonal structure was severely destroyed. The applicability of the obtained calcined materials as adsorbents for heavy metal ions from water was studied with the example of Pb(II). A high sorption capacity of 110 mg/g was obtained in batch experiments, at pH 5 and 4 h contact time. Full article

pH-responsive polyamidoamine (PAMAM) dendrimers are used as well-defined building blocks to design light-switchable nano-assemblies in solution. The complex interplay between the photoresponsive di-anionic azo dye Acid Yellow 38 (AY38) and the cationic PAMAM dendrimers of different generations is presented in this study. Electrostatic self-assembly involving secondary dipole–dipole interactions provides well-defined assemblies within a broad size range (10 nm–1 μm) with various shapes. The size and shape of these assemblies were determined using dynamic and static light scattering (DLS/SLS) and small-angle neutron scattering (SANS); ζ-potential measurements were performed to elucidate the charge characteristics, revealing the effective surface charge density of the nano-objects as an important parameter in the size and shape control. UV–vis spectroscopy and isothermal titration calorimetry (ITC) were employed to investigate the interaction on a molecular level and from a thermodynamic point of view. The results show that the amount of isomerized cis dye depends on the dendrimer generation because of a photoprotective effect through electrostatics for lower generations and through dipole–dipole interactions for higher generations; as the cis dye and trans dye bind with different strength, the amount of cis dye then again encodes the charge density and thereby the particle size and shape. Full article

Advanced batteries require advanced characterization techniques, and neutron scattering is one of the most powerful experimental methods available for studying next-generation battery materials. Neutron scattering offers a non-destructive method to probe the complex structural and chemical processes occurring in batteries during operation in truly in situ/in operando measurements with a high sensitivity to battery-relevant elements such as lithium. Neutrons have energies comparable to the energies of excitations in materials and wavelengths comparable to atomic distances in the solid state, thus giving access to study structural and dynamical properties of materials on an atomic scale. In this review, a broad overview of selected neutron scattering techniques is presented to illustrate how neutron scattering can be used to gain invaluable information of solid-state battery materials, with a focus on in situ/in operando methods. These techniques span multiple decades of length and time scales to uncover the complex processes taking place fundamentally on the atomic scale and to determine how these processes impact the macroscale properties and performance of functional battery systems. This review serves the solid-state battery research community by examining how the unique capabilities of neutron scattering can be applied to answer critical and unresolved questions of materials research in this field. A thorough and broad perspective is provided with numerous practical examples showing these techniques in action for battery research. Full article

The structure of the glassy Ge_xTe_1−x system, with x = 0.17, 0.21, 0.28, 0.30, and 0.45, is studied using the small-angle neutron scattering (SANS) technique. The very-low-momentum-transfer region of the diffractogram exhibits distinct behaviour depending on the germanium content. A similar conclusion is drawn from the analysis of the first diffraction peaks observed at higher angles. This system exhibits three composition regions with distinct behaviours: a first zone of low Ge content (up to about 20–25 at.%), a third zone richer in Ge (from about 30 at.% and above), and a second transitional zone between them. These changes are reflected in the parameters that govern Porod’s region, as well as in the region where the first diffraction peaks appear, corroborating previous observations made using other experimental and simulation techniques. Our study provides experimental evidence that could open up new possibilities for conducting simulations using neutron data. The results presented here show that increasing Ge content leads to a strengthening of the intermediate-range order at the expense of a weakening of the short-range order. Full article

Dual networks formed by entangled polymer chains and wormlike surfactant micelles have attracted increasing interest in their application as thickeners in various fields since they combine the advantages of both polymer- and surfactant-based fluids. In particular, such polymer-surfactant mixtures are of great interest as novel hydraulic fracturing fluids with enhanced properties. In this study, we demonstrated the effect of the chemical composition of an uncharged polymer poly(vinyl alcohol) (PVA) and pH on the rheological properties and structure of its mixtures with a cationic surfactant erucyl bis(hydroxyethyl)methylammonium chloride already exploited in fracturing operations. Using a combination of several complementary techniques (rheometry, cryo-transmission electron microscopy, small-angle neutron scattering, and nuclear magnetic resonance spectroscopy), we showed that a small number of residual acetate groups (2–12.7 mol%) in PVA could significantly reduce the viscosity of the mixed system. This result was attributed to the incorporation of acetate groups in the corona of the micellar aggregates, decreasing the molecular packing parameter and thereby inducing the shortening of worm-like micelles. When these groups are removed by hydrolysis at a pH higher than 7, viscosity increases by five orders of magnitude due to the growth of worm-like micelles in length. The findings of this study create pathways for the development of dual semi-interpenetrating polymer-micellar networks, which are highly desired by the petroleum industry. Full article

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^®. Full article

Photosynthetic organisms have established photoprotective mechanisms in order to dissipate excess light energy into heat, which is commonly known as non-photochemical quenching. Cyanobacteria utilize the orange carotenoid protein (OCP) as a high-light sensor and quencher to regulate the energy flow in the photosynthetic apparatus. Triggered by strong light, OCP undergoes conformational changes to form the active red state (OCP^R). In many cyanobacteria, the back conversion of OCP to the dark-adapted state is assisted by the fluorescence recovery protein (FRP). However, the exact molecular events involving OCP and its interaction with FRP remain largely unraveled so far due to their metastability. Here, we use small-angle neutron scattering combined with size exclusion chromatography (SEC-SANS) to unravel the solution structures of FRP-OCP complexes using a compact mutant of OCP lacking the N-terminal extension (^∆NTEOCP^O) and wild-type FRP. The results are consistent with the simultaneous presence of stable 2:2 and 2:1 FRP-^∆NTEOCP^O complexes in solution, where the former complex type is observed for the first time. For both complex types, we provide ab initio low-resolution shape reconstructions and compare them to homology models based on available crystal structures. It is likely that both complexes represent intermediate states of the back conversion of OCP to its dark-adapted state in the presence of FRP, which are of transient nature in the photocycle of wild-type OCP. This study demonstrates the large potential of SEC-SANS in revealing the solution structures of protein complexes in polydisperse solutions that would otherwise be averaged, leading to unspecific results. Full article