Hypothesis: Pea proteins can act not only as interfacial stabilizers of oil-in-water emulsions but also as gelling agents in the continuous phase. Protein gelation, rather than droplet jamming, may be the main mechanism of emulsion stability, providing a physical explanation for the creaminess of high-protein plant-based emulsions. Experimental: Spin-echo small angle neutron scattering (SESANS) with D₂O/H₂O contrast variation was used to study 15% pea protein dispersions and emulsions with 40–60% rapeseed oil, 7.5% protein at pH 3 to 6.5. SESANS investigates length scales up to tens of micrometres, enabling simultaneous analysis of protein networks and oil droplets without dilution. Complementary small angle X-ray/neutron scattering were used to validate protein aggregate size, and hydration. Findings: Protein dispersions at neutral pH formed mass fractal networks with small individual building blocks (radius ∼38 Å, hydration ∼70%). Emulsions consisted of oil droplets embedded in these networks, with droplet radii decreasing at higher oil fractions due to an effective higher protein concentration in the continuous phase, creating a denser network. Dispersions and emulsions at lower pH contained aggregated clusters of denatured proteins. These coarse and inhomogeneous networks gave increasing droplet radii at lower pH. Contrast variation enabled the separation of protein and oil droplet scattering, demonstrating that protein gelation rather than droplet jamming is the main mechanism of stability. This gives a physical explanation of the high viscosity of high-protein plant-based emulsions and is promising for these plant materials to be used as gelling agents in food applications.

Capillary suspensions are unique materials, in which the rheological properties can be tuned by controlling the particle network through capillary interactions. To gain insights into the influence of particle properties on the network formation and accompanying gel strength for water-absorbing, biopolymeric particles, protein particles of two different sizes and water absorption capacities (WACs) were prepared. Utilizing SESANS, we describe a novel approach towards detecting changes in water distribution between and within particles. While effects of WAC seemed to be overpowered by concurrent variations in surface roughness, a larger particle size or lower roughness led to a lower initial gel strength and a subsequent much larger relative increase in gel strength upon water addition. Even though similar maximum gel strengths were obtained, indicating that particle properties had a comparably small influence once capillary forces dominated the systems, particle size played a critical role for network collapse with increasing particle clustering at larger water volumes. The results pinpoint subsequent knowledge gaps in the existing literature and demonstrate the tunability of biopolymer-based capillary suspensions over a wide gel strength range by adjustment of particle properties. These insights offer exciting opportunities for application of capillary-force controlled systems in the food, pharmaceutical and cosmetic industries.

Tailoring the solution chemistry of metal halide perovskites requires a detailed understanding of precursor aggregation and coordination. In this work, we use various scattering techniques, including dynamic light scattering (DLS), small angle neutron scattering (SANS), and spin-echo SANS (SESANS) to probe the nanostructures from 1 nm to 10 μm within two different lead-halide perovskite solution inks (MAPbI ₃and a triple-cation mixed-halide perovskite). We find that DLS can misrepresent the size distribution of the colloidal dispersion and use SANS/SESANS to confirm that these perovskite solutions are mostly comprised of 1-2 nm-sized particles. We further conclude that if there are larger colloids present, their concentration must be <0.005% of the total dispersion volume. With SANS, we apply a simple fitting model for two component microemulsions (Teubner-Strey), demonstrating this as a potential method to investigate the structure, chemical composition, and colloidal stability of perovskite solutions, and we here show that MAPbI ₃solutions age more drastically than triple cation solutions.

By introducing hydrophilic polymers into silicone medical devices, highly beneficial biomedical properties can be realized. An established solution to introduce hydrophilic polymers is to form an interpenetrating polymer network (IPN) by performing the hydrogel synthesis in the presence of silicone swollen in supercritical carbon dioxide. The precise distribution of the two polymers is not known, and determining this is the goal of this study. Neutron scattering and microscopy were used to determine the distribution of the hydrophilic guest polymer. Atomic force microscopy revealed that the important length scale on the surface of these materials is 10–100 nm, and spin-echo small-angle neutron scattering (SESANS) on IPNs submerged in D₂O revealed structures of the same scale within the interior and enabled quantification of their size. SESANS with hydration by D₂O proved to be the only scattering technique that could determine the structure of the bulk of these types of materials, and it should be used as an important tool for characterizing polymer medical devices.

The initial formation stages of surfactant-templated silica thin films which grow at the air-water interface were studied using combined spin-echo modulated small-angle neutron scattering (SEMSANS) and small-angle neutron scattering (SANS). The films are formed from either a cationic surfactant or nonionic surfactant (C16EO8) in a dilute acidic solution by the addition of tetramethoxysilane. Previous work has suggested a two stage formation mechanism with mesostructured particle formation in the bulk solution driving film formation at the solution surface. From the SEMSANS data, it is possible to pinpoint accurately the time associated with the formation of large particles in solution that go on to form the film and to show their emergence is concomitant with the appearance of Bragg peaks in the SANS pattern, associated with the two-dimensional hexagonal order. The combination of SANS and SEMSANS allows a complete depiction of the steps of the synthesis that occur in the subphase.

This paper reports on the two-scale fractal structure of chromatin organization in the nucleus of the HeLa cell. Two neutron scattering methods, small-angle neutron scattering (SANS) and spin-echo SANS, are used to unambiguously identify the large-scale structure as being a logarithmic fractal with the correlation function (r) - ln(r/E). The smaller-scale structural level is shown to be a volume fractal with dimension DF = 2.41. By definition, the volume fractal is self-similar at different scales, while the logarithmic fractal is hierarchically changed upon scaling. As a result, the logarithmic fractal is more compact than the volume fractal but still has a rather high surface area, which provides accessibility at all length scales. Apparently such bi-fractal chromatin organization is the result of an evolutionary process of optimizing the compactness and accessibility of gene packing. As they are in a water solution, the HeLa nuclei tend to agglomerate over time. The large-scale logarithmic fractal structure of chromatin provides the HeLa nucleus with the possibility of penetrating deeply into the adjacent nucleus during the agglomeration process. The interpenetration phenomenon of the HeLa nuclei shows that the chromatin-free space of one nucleus is not negligible but is as large as the volume occupied by chromatin itself. It is speculated that it is the logarithmic fractal architecture of chromatin that provides a comfortable compartment for this most important function of the cell.

We investigate the morphological development of polystyrene (PS)-C ₆₀ nanocomposites along the length of a prototype co-rotating twin-screw extruder with sampling capabilities. The effects of C ₆₀ concentration and output on the morphological evolution along the extruder are studied employing a suite of characterization techniques covering a wide range of length-scales, thereby shedding new light on the dispersion mechanism in this model system. We show that the relatively new spin-echo small-angle neutron scattering (SESANS) technique is well suited to probe both the distribution and the dispersion of C ₆₀ . SESANS complements optical microscopy (OM) data as it covers sampling areas several orders of magnitude larger than OM. The multi-scale morphological information conveyed by OM, SESANS, SANS and rheological data shows that for larger outputs, C ₆₀ agglomerates are eroded as they travel along the extruder, resulting in C ₆₀ dispersion and distribution at both molecular and micrometric levels. The picture is more complex when smaller feed rates are used, as the evolution of C ₆₀ dispersion depends on the C ₆₀ loading. For larger C ₆₀ contents, agglomeration develops along the extruder, whereas dispersion is improved for smaller C ₆₀ contents. Overall, it is concluded that an over-high feed rate in extrusion does not necessarily result in a bigger size of the nanoparticle agglomerates because of the complex interplay between stresses and residence time.

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

The closed porous structure in ceramic materials is investigated by spin-echo small-angle neutron scattering. A series of ceramic samples of oxygen–ion conductors based on bismuth molybdate with the general formula Bi_12.8X_0.2Mo₅O_{34 ± δ} (X = Mg, Ba, Ca, Sr) is obtained by powder sintering for 6−45 h at a temperature close to the melting point. The samples are characterized by scanning electron microscopy and X-ray fluorescence analysis. It is found that they had a stoichiometric chemical composition, are singlephase, and contain clean pores between crystal grains. The pore size is determined by spin-echo small-angle neutron scattering and ranges from 2.2 to 3.5 μm. It is demonstrated that longer sintering times correspond to larger pores (the increase in their average diameter is as large as 30%). It is found that the studied materials lack a fractal pore structure.