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Ionically crosslinked hydrogels containing metal coordination motifs have piqued the interest of researchers in recent decades due to their self-healing and adhesive properties. In particular, catechol-functionalized bulk hydrogels have received a lot of attention because of their bioinspired nature. By contrast, very little is known about thin viscoelastic membranes made using similar chelator–ion pair motifs. This shortcoming is surprising because the unique interfacial properties of these membranes, namely, their self-healing and adhesion, would be ideal for capsule shells, adhesives, or for drug delivery purposes. We recently demonstrated the feasibility to fabricate 10 nm thick viscoelastic membranes from catechol-functionalized surfactants that are ionically crosslinked at the liquid/liquid interface. However, it is unclear if the vast know-how existing on the influence of the chelator–ion pair on the mechanical properties of ionically crosslinked three-dimensional (3D) hydrogels can be translated to two-dimensional (2D) systems. To address this question, we compare the dynamic mechanical properties of ionically crosslinked pyrogallol functionalized hydrogels with those of viscoelastic membranes that are crosslinked using the same chelator–ion pairs. We demonstrate that the storage and loss moduli of viscoelastic membranes follow a trend similar to that of the hydrogels, with the membrane becoming stronger as the ion–chelator affinity increases. Yet, membranes relax significantly faster than bulk equivalents. These insights enable the targeted design of viscoelastic, adhesive, self-healing membranes possessing tunable mechanical properties. Such capsules can potentially be used, for example, in cosmetics, as granular inks, or with additional work that includes replacing the fluorinated block by a hydrocarbon-based one in drug delivery and food applications.

Magnetic small‐angle neutron scattering (SANS) is ideally suited to providing direct reciprocal‐space information on long‐wavelength magnetic modulations, such as helicoids, solitons, merons or skyrmions. SANS of such structures in thin films or micro‐structured bulk materials is strongly limited by the tiny scattering volume vis a vis the prohibitively high background scattering by the substrate and support structures. Considering near‐surface scattering just above the critical angle of reflection, where unwanted signal contributions due to substrate or support structures become very small, it is established that the scattering patterns of the helical, conical, skyrmion lattice and fluctuation‐disordered phases in a polished bulk sample of MnSi are equivalent for conventional transmission and near‐surface SANS geometries. This motivates the prediction of a complete repository of scattering patterns expected for thin films in the near‐surface SANS geometry for each orientation of the magnetic order with respect to the scattering plane., Near‐surface SANS is discussed for its potential as a probe of long‐wavelength magnetic modulations in specimens with reduced sample dimensions.

Oil-in-water (O/W) microemulsions typically feature a low viscosity and exhibit the ordinary viscosity reduction as a function of temperature. However, for certain applications avoiding or even reverting the temperature trend might be required. This can be conceived by adding thermoresponsive (TR) block copolymers that induce network formation as temperature rises. Accordingly, various ME–polymer mixtures were studied for which three different block copolymer architectures of BAB*, B2AB*, and B(AB*)2 type were employed. Here, “B” represents a permanently hydrophobic, “A” a permanently hydrophilic, and “B*” a TR block. For the TR-block, three different poly(acrylamide)s, namely poly(N-n-propylacrylamide) (pNPAm), poly(N,N-diethylacrylamide) (pDEAm), and poly(N-isopropylacrylamide) (pNiPAm), were used, which all exhibit a lower critical solution temperature (LCST). For a well selected ME concentration, these block copolymers lead to a viscosity enhancement with rising temperature. At a polymer concentration of about 22 g L-1, the most pronounced enhancement was observed for the pNPAm-based systems with factors up to 3, 5, and 8 for BAB*, B2AB*, and B(AB*)2, respectively. This phenomenon is caused by the formation of a transitory network mediated by TR-blocks, as evidenced by the direct correlation between the attraction strength and the viscosity enhancement. For applications requiring a high hydrophobic payload, which is attained via microemulsion droplets, this kind of tailored temperature-dependent viscosity control of surfactant systems should therefore be advantageous.

A dilute ensemble of randomly oriented non-interacting spherical nanomagnets is considered, and its magnetization structure and ensuing neutron scattering response are investigated by numerically solving the Landau–Lifshitz equation. Taking into account the isotropic exchange interaction, an external magnetic field, a uniaxial magnetic anisotropy for the particle core, and in particular the Néel surface anisotropy, the magnetic small-angle neutron scattering cross section and pair-distance distribution function are calculated from the obtained equilibrium spin structures. The numerical results are compared with the well known analytical expressions for uniformly magnetized particles and provide guidance to the experimentalist. In addition, the effect of a particle-size distribution function is modelled.

The quantitative characterization of small nano-sized precipitates poses genuine challenges and is often deficient in accuracy due to the inherent limitations inevitably associated with the individual experimental techniques. A convenient solution is to utilize multiple complementary techniques. The present work demonstrates an effective way to reliably quantify nano-sized precipitates using a combination of complementary techniques of atom probe tomography (APT), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). As a case study, the size (radius, r), number density (NP), volume fraction (ϕ), and chemical composition of Cr-rich α′ precipitates are determined in Fe–20 at% Cr alloy, thermally aged at 773 K for 1,000 h. This combinatorial approach utilizes the strength of each technique in such a way that the overall accuracy of quantitative precipitation analysis improves significantly. For example, the superior spatial resolution makes TEM the appropriate technique to estimate the size and size distribution of the precipitates, while APT provides the chemical composition. Similarly, SANS analysis incorporates both the size and the compositional information thus derived independently and provides statiscally averaged quantitative analysis overcoming the field-of-view limitations of both TEM and APT. This combinatorial approach improves the accuracy of quantification and provides the true representation of the microstructure.

open access article OBJECTIVES The triblock copolymer Pluronic® is widely used in the personal care industry, including sun protection, for its film forming and solubilisation capabilities. In this study, the effect of three commonly used organic UV filters (ethylhexyl methoxycinnamate (EMC), ethylhexyl triazone (EHT) and avobenzone (AVB)) on the structure of Pluronic P123 micelles was investigated. METHODS The Pluronic P123 micelle structure has been investigated using dynamic surface tension, nuclear magnetic resonance (NMR) and small-angle neutron scattering (SANS). RESULTS Dynamic surface tension results show strong interactions between the UV filters and Pluronic® evident by sharp changes in the surface activity of the latter. The NMR results have revealed the creation of a hydrophobic microenvironment special to the Pluronic PPO core group in the presence of UV filters. Some interaction with the hydrophilic EO was also recorded, albeit weaker. This is further confirmed by SANS, where the Pluronic P123 micelles interacted with varying strengths with the UV filters, resulting in sharp changes in their size and shape. CONCLUSIONS We have demonstrated the sensitivity of the Pluronic P123 micelles to the presence of various UVA/B filters. The micelles shape varied from spherical to cylindrical as the concentration and type of the UV filters were varied. These variations in the shape are expected to have a significant effect on the sun protection factor (SPF), as it affects the solubilisation of the UV filters within a formulation in addition to the formulations’ rheological profile and film forming behaviour.

The MATLAB-based software tool MuMag2022 is presented for the analysis of magnetic-field-dependent unpolarized small-angle neutron scattering (SANS) data of bulk ferromagnets such as elemental nanocrystalline ferromagnets, magnetic nanocomposites or magnetic steels. On the basis of the micromagnetic theory for the magnetic SANS cross section, the program analyzes unpolarized total (nuclear and magnetic) SANS data within the approach-to-saturation regime. The main features of MuMag2022 are the estimation of the exchange-stiffness constant, and of the strength and spatial structure of the magnetic anisotropy field and the magnetostatic field due to longitudinal magnetization fluctuations. MuMag2022 is open source and available as a standalone executable for Windows at https://mumag.uni.lu. EMJ acknowledges the support of a Beca Concepción Arenal fellowship (BDNS: 406333, Gobierno de Cantabria, Spain). MPA and AM thank the National Research Fund of Luxembourg for financial support (AFR grant No. 15639149).

On the basis of Brown's static equations of micromagnetics, the uniaxial polarization of the scattered neutron beam of a bulk magnetic material is computed. The approach considers a Hamiltonian that takes into account the isotropic exchange interaction, the antisymmetric Dzyaloshinskii–Moriya interaction, magnetic anisotropy, the dipole–dipole interaction and the effect of an applied magnetic field. In the high-field limit, the solutions for the magnetization Fourier components are used to obtain closed-form results for the spin-polarized small-angle neutron scattering (SANS) cross sections and the ensuing polarization. The theoretical expressions are compared with experimental data on a soft magnetic nanocrystalline alloy. The micromagnetic SANS theory provides a general framework for polarized real-space neutron methods, and it may open up a new avenue for magnetic neutron data analysis on magnetic microstructures.

The small‐angle neutron scattering data of nanostructured magnetic samples contain information regarding their chemical and magnetic properties. Often, the first step to access characteristic magnetic and structural length scales is a model‐free investigation. However, due to measurement uncertainties and a restricted q range, a direct Fourier transform usually fails and results in ambiguous distributions. To circumvent these problems, different methods have been introduced to derive regularized, more stable correlation functions, with the indirect Fourier transform being the most prominent approach. Here, the indirect Fourier transform is compared with the singular value decomposition and an iterative algorithm. These approaches are used to determine the correlation function from magnetic small‐angle neutron scattering data of a powder sample of iron oxide nanoparticles; it is shown that with all three methods, in principle, the same correlation function can be derived. Each method has certain advantages and disadvantages, and thus the recommendation is to combine these three approaches to obtain robust results., Three different approaches are compared for determination of the correlation function from the small‐angle neutron scattering data of a powder sample of iron oxide nanoparticles.

[Hypothesis] l-carnitines in our body systems can be readily converted into acyl-l-carnitines which have a prominent place in cellular energy generation by supporting the transport of long-chain fatty acids into mitochondria. As biocompatible surfactants, acyl-l-carnitines have potential to be useful in technical, personal care and healthcare applications. However, the lack of understanding of the effects of their molecular structures on their physical properties has constrained their potential use., [Experiments] This work reports the study of the influence of the acyl chain lengths of acyl-l-carnitines (CnLC) on solubility, surface adsorption and aggregation. Critical micellar concentrations (CMCs) of CnLC were determined by surface tension measurements. Neutron reflection (NR) was used to further examine the structure and composition of the adsorbed CnLC layer. The structural changes of the micellar aggregates under different concentrations of CnLC, pH and ionic strength were determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS)., [Findings] C12LC is fully soluble over a wide temperature and concentration range. There is however a strong decline of solubility with increasing acyl chain length. The adsorption and aggregation behavior of C14LC was therefore studied at 30 °C and C16LC at 45 °C. The solubility boundaries displayed distinct hysteresis with respect to heating and cooling. The CMCs of C12LC, C14LC and C16LC at pH 7 were 1.1 ± 0.1, 0.10 ± 0.02 and 0.010 ± 0.005 mM, respectively, with the limiting values of the area per molecule at the CMC being 45.4 ± 2, 47.5 ± 2 and 48.8 ± 2 Å2 and the thicknesses of the adsorbed CnLC layers at the air/water interface increasing from 21.5 ± 2 to 22.6 ± 2 to 24.2 ± 2 Å, respectively. All three surfactants formed core–shell spherical micelles with comparable dimensional parameters apart from an increase in core radius with acyl chain length. This study outlines the effects of acyl chain length on the physicochemical properties of CnLCs under different environmental conditions, serving as a useful basis for developing their potential applications., We thank Lonza for funding this project under the grant number P121881. The provision of neutron beam time from ISIS Neutron Facility (LOQ, RB1920293 and Surf, RB1920156) and ILL Neutron Facility (D11, 9-10-1613 and FIGARO, 9-13-840) is acknowledged. We also appreciate the SasView, developed by NSF award DMR-0520547, and Igor pro.

Hypothesis Complex fluids comprising polymers and surfactants exhibit interesting properties which depend on the overall composition and solvent quality. The ultimate determinants of the macroscopic properties are the nano-scale association domains. Hence it is important to ascertain the structure and composition of the domains, and how they respond to the overall composition. Experiments The structure and composition of mixed micelles formed in aqueous solution between poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronics or Poloxamers) and the ionic surfactant sodium dodecylsulfate (SDS) are determined from an analysis of small-angle neutron scattering (SANS) intensity data obtained at different contrasts. Different polymers and concentrations have been probed. Findings The SDS + Pluronic mixed micelles include polymer and some water in the micelle core that is formed primarily by alkyl chains. This is different than what was previously reported, but is consistent with a variety of experimental observations. This is the first report on the structure of SDS + Pluronic P123 (EO19PO69EO19) assemblies. The effects on the mixed micelle structure and composition of the surfactant concentration and the polymer hydrophobicity are discussed here in the context of interactions between the different components.

Nanosized probes that report their changes in dimensions within networks in response to environmental stimuli are potentially important for applications such as drug delivery, load-supporting hydrogels and soft robotics. Recently, we developed a fluorescent pH-responsive nanogel (NG) that used Forster-resonance energy transfer (FRET) to report changes in the probe separation and NG swelling within hydrogels using photoluminescence (PL) spectroscopy. However, FRET cannot measure nanoparticle dimensions and is subject to artefacts. Here, we report the use of small-angle neutron scattering (SANS) to study both the NGs in dispersion and in polyacrylamide (PAAm) gels as a function of pH. We compare the PL and SANS data for both systems and as a function of pH. The SANS data for the dispersed NGs indicate that they have a core–shell structure with a swollen mesh size of ∼1.0 nm. We hypothesized that the NGs inside the PAAm gel would show the same general changes in scattering as the pH is increased, as observed for the dispersed NGs, and this is confirmed by the data. In summary, the data confirm that PL is a suitable (accessible) method for reporting internal environmental changes within gels using NG probes.

Bulk metallic glasses (BMGs) are thermodynamically metastable. As such, crystallization occurs when a BMG is thermally annealed at a temperature above the glass transition temperature. While extensive studies have been performed on the crystallization kinetics of BMGs, most of them have focused on the amorphous-to-crystalline structural ordering, and little attention has been paid to chemical distribution and its relationship with the structural ordering during the crystallization process. In this paper, a new approach, with simultaneous differential scanning calorimetry (DSC) and small angle neutron scattering (SANS) measurements, was applied to study in situ the crystallization of a Zr45.5Cu45.5Al9 BMG upon isothermal annealing at a temperature in the supercooled liquid region. Quantitative analysis of the DSC and SANS data showed that the structural evolution during isothermal annealing could be classified into three stages: (I) incubation; (II) amorphous-to-crystalline structural ordering; (III) continuous chemical redistribution. This finding was validated by composition analysis with atom probe tomography (APT), which further identified a transition region formed by expelling Al into the matrix. The transition region, with a composition of (Cu,Al)50Zr50, served as an intermediate step facilitating the formation of a thermodynamically stable crystalline phase with a composition of (Cu,Al)10Zr7.

Hypothesis Weakly hydrated nanometric ions, called superchaotropes, were recently shown to adsorb strongly to non-ionic surfaces affecting drastically the surface’s physical–chemical properties due to a charging effect. Superchaotropic ions could serve as stabilizing agents for non-ionic colloidal systems, such as non-ionic surfactant foams. Experiments We study foams of the non-ionic surfactant BrijO10 (C18:1E10) without and in presence of the superchaotropic Keggin-ion SiW12O404− (SiW). The foams are investigated under free drainage conditions by image analysis and conductimetry to reveal the effect of SiW on the foam stability, liquid drainage, and bubble size. Additionally, small angle neutron scattering on the same foams, but in a dry quasi-stationary state, provides insight into effects of SiW on the foam films. Findings SiW strongly stabilizes non-ionic surfactant foams at millimolar concentrations by inducing electrostatic repulsions between foam film interfaces resulting in thicker and monodisperse foam films. A similar effect is observed with the ionic surfactant sodium dodecylsulfate (SDS) but to a lesser extent and with a different mechanism. At the foam films’ interface, SiW adsorbs to the polar non-ionic surfactant heads driven by the superchaotropic effect whereas DS− anchors between non-ionic surfactant alkyl chains by the hydrophobic effect. The potential of superchaotropic ions as foam stabilizers is herein demonstrated.

Deuterium is a natural low abundance stable hydrogen isotope that in high concentrations negatively affects growth of cells. Here, we have studied growth of Escherichia coli MG1655, a wild-type laboratory strain of E. coli K-12, in deuterated glycerol minimal medium. The growth rate and final biomass in deuterated medium is substantially reduced compared to cells grown in ordinary medium. By using a multi-generation adaptive laboratory evolution-based approach we have isolated strains that show increased fitness in deuterium-based growth media. Whole-genome sequencing identified the genomic changes in the obtained strains and show that there are multiple routes to genetic adaptation to growth in deuterium-based media. By screening a collection of single-gene knockouts of non-essential genes no specific gene was found to be essential for growth in deuterated minimal medium. Deuteration of proteins is of importance for NMR spectroscopy, neutron protein crystallography, neutron reflectometry, and small angle neutron scattering. The laboratory evolved strains, with substantially improved growth rate, were adapted for recombinant protein production by T7 RNA polymerase overexpression systems and shown to be suitable for efficient production of perdeuterated soluble and membrane proteins for structural biology applications. This article is protected by copyright. All rights reserved.

The microstructure and mechanical properties of 6 wt.% Mn-doped martensitic steel have been investigated through a combination of electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and small-angle neutron scattering (SANS). The 6 wt.% Mn-doped steel exhibits a yield strength of ~1.83 GPa and an elongation-to-failure of ~7% under peak aging, and the ~853 MPa of precipitation strengthening is much higher than that observed in the 1.5 wt.% and 3 wt.% Mn-doped steels. The steel is composed of α’-martensite and slightly equiaxed α-ferrite together with a high proportion (~62.3%) of low-angle grain boundaries, and 6 wt.% Mn doping and the aging treatment have an effect on the matrix’s microstructure. However, 6 wt.% Mn doping can obviously increase the mean size of the Cu/NiAl nanoparticles by enhancing the chemical driving force of the Mn partitioning on the NiAl nanoparticles, which differs from the refining effect on the nanoparticles in 3 wt.% Mn-doped steels. Furthermore, larger Cu/NiAl nanoparticles can significantly improve the yield strength of martensitic steel through precipitation-strengthening mechanisms.

In this study, we used small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) to investigate the formation process of silver (Ag) nanoparticles (NPs) in water-in-oil (w/o) reverse microemulsions comprising sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water, and organic solvents (such as benzene, octane, and decane) by the photoreduction of silver perchlorate (AgClO4). Combining SANS and SAXS, the structural changes in the w/o microemulsions before and after the formation of Ag NPs via photoreduction were quantitatively evaluated. From the SANS experiments performed using the contrast-variation method, the size of water cores containing Ag NPs and the thickness of the AOT shells were calculated using the core-shell hard-sphere model. The size of the Ag NPs and their aggregates was calculated via SAXS analysis based on the polydisperse sphere model with a Schulz-Zimm distribution. We found that aggregates of three or four primary Ag NPs are formed by, first, the aggregation of water droplets through the entanglement of the tails of the AOT shell, followed by the self-assembly of Ag NPs into their aggregates because of particle-particle attractive interactions.

We present a systematic study using real-time small-angle neutron scattering (SANS) and optical microscopy to follow the protein crystallization process in the presence of a metastable intermediate...

The aims of this work were to evaluate the effect of freezing and thawing stresses on lactate dehydrogenase (LDH) stability under three conditions. (i) In a solution buffered with sodium phosphate (NaP; 10 and 100 mM). The selective crystallization of disodium hydrogen phosphate during freezing caused a pronounced pH shift. (ii) In a solution buffered with histidine, where there was no pH shift due to buffer salt crystallization. (iii) At different concentrations of LDH so as to determine the self-stabilizing ability of LDH. The change in LDH tetrameric conformation was measured by small-angle neutron scattering (SANS). The pH of the phosphate buffer solutions was monitored as a function of temperature to quantify the pH shift. The conditions of buffer component crystallization from solution were identified using low-temperature X-ray diffractometry. Dynamic light scattering (DLS) enabled us to determine the effect of freeze-thawing on the protein aggregation behavior. LDH, at a high concentration (1000 μg/mL; buffer concentration 10 mM), has a pronounced self-stabilizing effect and did not aggregate after five freeze-thaw cycles. At lower LDH concentrations (10 and 100 μg/mL), only with the selection of an appropriate buffer, irreversible aggregation could be avoided. While SANS provided qualitative information with respect to protein conformation, the insights from DLS were quantitative with respect to the particle size of the aggregates. SANS is the only technique which can characterize the protein both in the frozen and thawed states.

Biopharmaceutical formulations may be compromised by freezing, which has been attributed to protein conformational changes at a low temperature, and adsorption to ice-liquid interfaces. However, direct measurements of unfolding/conformational changes in sub-0 °C environments are limited because at ambient pressure, freezing of water can occur, which limits the applicability of otherwise commonly used analytical techniques without specifically tailored instrumentation. In this report, small-angle neutron scattering (SANS) and intrinsic fluorescence (FL) were used to provide in situ analysis of protein tertiary structure/folding at temperatures as low as -15 °C utilizing a high-pressure (HP) environment (up to 3 kbar) that prevents water from freezing. The results show that the α-chymotrypsinogen A (aCgn) structure is reasonably maintained under acidic pH (and corresponding pD) for all conditions of pressure and temperature tested. On the other hand, reversible structural changes and formation of oligomeric species were detected near -10 °C via HP-SANS for ovalbumin under neutral pD conditions. This was found to be related to the proximity of the temperature of cold denaturation of ovalbumin (TCD ∼ -17 °C; calculated via isothermal chemical denaturation and Gibbs-Helmholtz extrapolation) rather than a pressure effect. Significant structural changes were also observed for a monoclonal antibody, anti-streptavidin IgG1 (AS-IgG1), under acidic conditions near -5 °C and a pressure of ∼2 kbar. The conformational perturbation detected for AS-IgG1 is proposed to be consistent with the formation of unfolding intermediates such as molten globule states. Overall, the in situ approaches described here offer a means to characterize the conformational stability of biopharmaceuticals and proteins more generally under cold-temperature stress by the assessment of structural alteration, self-association, and reversibility of each process. This offers an alternative to current ex situ methods that are based on higher temperatures and subsequent extrapolation of the data and interpretations to the cold-temperature regime.

Small-angle neutron scattering (SANS) is widely used in structural analysis of complex liquid dispersions. An essential feature of SANS experiments for such systems is hydrogen/deuterium isotopic s...

Abstract Water interactions and accessibility of the nanoscale components of plant cell walls influence their properties and processability in relation to many applications. We investigated the water-accessibility of nanoscale pores within the fibrillar structures of unmodified Norway spruce cell walls by small-angle neutron scattering (SANS) and Fourier-transform infra-red (FTIR) spectroscopy. The different sensitivity of SANS to hydrogenated ($$\hbox {H}_2\hbox {O}$$ H 2 O ) and deuterated water ($$\hbox {D}_2\hbox {O}$$ D 2 O ) was utilized to follow the exchange kinetics of water among cellulose microfibrils. FTIR spectroscopy was used to study the time-dependent re-exchange of OD groups to OH in wood samples transferred from liquid $$\hbox {D}_2\hbox {O}$$ D 2 O to $$\hbox {H}_2\hbox {O}$$ H 2 O . In addition, the effects of drying on the nanoscale structure and its water-accessibility were addressed by comparing SANS results and the kinetics of water exchange between never-dried and dried/rewetted wood samples. The results of the kinetic analyses allowed to identify two processes with different timescales. The diffusion-driven exchange of water in the spaces between microfibrils, which was observed with both SANS and FTIR, takes place within minutes and rather homogeneously. The second, slower process appeared only in the OD/OH re-exchange followed by FTIR, and it still continued after several weeks of immersion in $$\hbox {H}_2\hbox {O}$$ H 2 O . SANS could not detect any significant difference between the never-dried and dried/rewetted samples, whereas FTIR revealed a small portion of OD groups that resisted the re-exchange and this portion became larger with drying. Graphic abstract

This work presents a study on the electrical and structural properties of percolating composites based on graphite (Gt) particles dispersed with various concentrations into an insulating polyester matrix (PES). Their structural characterization was performed using small-angle neutron scattering (SANS), providing information about the dispersion of fillers within the matrix. Electrical measurements were carried out in the frequency range from 1 Hz to 10 MHz and temperature from 30°C to 100°C. It was found that when the filler concentration is above the percolation threshold and the temperature above the glass transition, the positive temperature coefficient of resistance is identified. The mechanism responsible for this behavior was attributed to the tunneling effect. The Nyquist representations of the complex impedance spectra were modeled using the Cole–Cole model. The obtained values of the α exponent that gauges the broadening of the loss spectrum suggest a behavior close to a model of a single relaxation time.

Developing small-angle neutron scattering techniques at compact accelerator-driven neutron sources (CANS) is of great importance for expanding the user community and advancing CANS capability. At the Compact Pulsed Hadron Source (CPHS) at Tsinghua University, neutron-focusing mirrors are under intensive research to address the challenge. A grazing-incidence focusing SANS (gif-SANS) project is initialized. It employs a nested supermirror assembly with a large collecting area to achieve ⩾ 10 5 n/s neutron intensity at Q min ⩽ 0.007 Å − 1 . It will equip two detectors, one being a 3He detector for normal Q-range measurements, and the other being a high-resolution detector for extending the Q min down to 10 − 3 Å − 1 . In this work, we present the conceptual design of the gif-SANS at CPHS. Such a scheme is conducive to enable high-performance SANS measurements at CANS.

Small-angle neutron scattering (SANS) is performed to analyse the microstructural state of a reference CuCrZr material with carefully controlled heat treatments, small-scale manufacturing mock-ups of assemblies and high-heat-flux-exposed mock-ups. The work demonstrates that SANS can be used for millimetre-scale analysis of small engineering components with minimal surface preparation., Small-angle neutron scattering (SANS) is performed to analyse the microstructural state of a reference CuCrZr material with carefully controlled heat treatments, small-scale manufacturing mock-ups of assemblies and high-heat-flux-exposed mock-ups for fusion reactor components. The information derived from the SANS data corresponds well to existing literature data based on microscopic-scale techniques, but is obtained at millimetre scale with minimal surface preparation. The manufacturing method and high-heat-flux testing conditions are confirmed to have little impact on the microstructural properties, demonstrating the validity of these treatments for scaled-up reactor components.

Liquid lipid nanoparticles (LLN) are oil-in-water nanoemulsions of great interest in the delivery of hydrophobic drug molecules. They consist of a surfactant shell and a liquid lipid core. The small size of LLNs makes them difficult to study, yet a detailed understanding of their internal structure is vital in developing stable drug delivery vehicles (DDVs). Here, we implement machine learning techniques alongside small angle neutron scattering experiments and molecular dynamics simulations to provide critical insight into the conformations and distributions of the lipid and surfactant throughout the LLN. We simulate the assembly of a single LLN composed of the lipid, triolein (GTO), and the surfactant, Brij O10. Our work shows that the addition of surfactant is pivotal in the formation of a disordered lipid core; the even coverage of Brij O10 across the LLN shields the GTO from water and so the lipids adopt conformations that reduce crystallisation. We demonstrate the superior ability of unsupervised artificial neural networks in characterising the internal structure of DDVs, when compared to more conventional geometric methods. We have identified, clustered, classified and averaged the dominant conformations of lipid and surfactant molecules within the LLN, providing a multi-scale picture of the internal structure of LLNs.

Small-angle neutron scattering data on aqueous solutions of wormlike micelles of an anionic surfactant of potassium oleate in the presence of low molecular weight salt KCl have been studied for a wide range of surfactant concentrations. It is shown that, as the concentration of micelles in the network increases, the scattering intensity decreases because of the structure factor for small scattering vectors. The parameters of the local structure of micelles, which are independent of the surfactant concentration, are determined in the range of medium values of the scattering vectors. The values of the persistence length of wormlike micelles are obtained for small concentrations of potassium oleate. The correct persistence length of the micelles is found upon extrapolating the obtained values to the zero surfactant concentration, where there is no interaction between the micelles.

Data on the morphology of carbon allotrope nanoparticles in an isotactic polypropylene (IPP) matrix are analyzed. They are obtained using the small-angle neutron scattering method and a YuMO spectrometer at the IBR2 reactor of the Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Physics (Dubna, Russian Federation). The fractal dimensionality is calculated, the form is reconstructed, and the geometric dimensions of the obtained particles and aggregates of single-wall carbon nanotubes (SWCNTs) in the IPP volume taken in concentrations of 1.2, 2.6, and 8 wt % are determined using ATSAS software. It is established that nanotubes form fractal nanoobjects with a rough surface in the IPP volume. Composite IPP/SWCNT systems are polydisperse to a significant degree; nanotubes twist into coils and knots and become more densely packed; in the polymer volume, the dimensions of the formed nanoparticles and their aggregates are several times larger than the initial ones used during synthesis. A model of knot formation in polymer materials based on calculating the asymptotic Hopf invariant and the lattice fractal dimensionality is used in this paper to interpret the results and predictions of the possible morphology forming in samples of such a type. The energies and probabilities of knot formation are estimated qualitatively using the Monte Carlo method.

There is an increased interest in the use of natural surfactant as replacements for synthetic surfactants due to their biosustainable and biocompatible properties. A category of natural surfactants which are attracting much current interest is the triterpenoid saponins; surface active components found extensively in a wide range of plant species. A wide range of different saponin structures exist, depending upon the plant species they are extracted from; but regardless of the variation in structural details they are all highly surface active glycosides. Greater exploitation and application requires a characterisation and understanding of their basic adsorption and self-assembly properties.HypothesisGlycyrrhizic acid, extracted from Licorice root, is a monodesmosidic triterpenoid saponin. It is widely used in cosmetic and pharmaceutical applications due to its anti-inflammatory properties, and is an ingredient in foods as a sweetener additive. It has an additional attraction due to its gel forming properties at relatively low concentrations. Although it has attracted much recent attention, many of its basic surface active characteristics, adsorption and self-assembly, remain relatively unexplored. How the structure of the Glycyrrhizic acid saponin affects its surface active properties and the impact of gelation on these properties are important considerations, and to investigate these are the focus of the study.ExperimentsIn this paper the adsorption properties at the air-water interface and the self-assembly in solution have been investigated using by neutron reflectivity and small angle neutron scattering; in non-gelling and gelling conditions.FindingsThe adsorption isotherm is determined in water and in the presence of gelling additives, and compared with the adsorption behaviour of other saponins. Gelation has minimal impact on the adsorption; apart from producing a rougher surface with a surface texture on a macroscopic length scale. Globular micelles are formed in aqueous solution with modest anisotropy, and are compared with the structure of other saponin micelles. The addition of gelling agents results in only minimal micelle growth, and the solutions remain isotropic under applied shear flow.

Perfume solubilization is an important process in the production of commercial products such as beverages, foods, and cosmetics. In the present study, small-angle neutron scattering (SANS) experiments were performed to investigate the solubilization behavior of perfumes in cetyltrimethylammonium bromide (CTAB) micelles. The solubilization of linalool (LL) and l-menthol (MT), which are relatively hydrophilic perfumes, did not change the size of the CTAB micelles although the perfumes were incorporated in the micelles, as indicated by a decrease in scattering length density. On the other hand, the solubilization of d-limonene (LN), a hydrophobic perfume, led to the swelling of CTAB micelles. An internal contrast variation SANS study was performed by the deuteration of CTAB molecules to directly observe the perfumes in the micelles. The radius of d-CTAB micelles solubilizing LL or MT corresponds to that of h-CTAB, which indicates that these perfumes are accommodated in the palisade layers of the micelles and are homogeneously distributed in the micelles. On the other hand, LN formed small droplets, as indicated by the SANS profile, which implies the solubilization of LN molecules in the core of the CTAB micelles. We found that the relatively hydrophilic perfumes (LL and MT) show less impact on the sizes of the cationic micelles in comparison to nonionic micelles. Thus, the internal contrast variation method of SANS allowed the direct observation of the solubilization sites of perfumes with different hydrophilicity-hydrophobicity balances. This method is a powerful tool to determine the solubilization states that affect the solubilization capacity, volatilization, or release speed of perfumes.

Nanodiamonds combine unique mechanical, thermodynamic and optical properties of diamond with the peculiarities of colloidal dimensions and wide possibilities of chemical modification of their surfa...

Glycans of cellular glycoconjugates serve as biochemical signals for a multitude of (patho)physiological processes via binding to their receptors (e.g. lectins). In the case of human adhesion/growth-regulatory galectin-1 (Gal-1), small angle neutron scattering and fluorescence correlation spectroscopy have revealed a significant decrease of its gyration radius and increase of its diffusion coefficient upon binding lactose, posing the pertinent question on the nature and region(s) involved in the underlying structural alterations. Requiring neither a neutron source nor labeling, diffusion measurements by 1H NMR spectroscopy are shown here to be sufficiently sensitive to detect this ligand-induced change. In order to figure out which region(s) of Gal-1 is (are) affected at the level of peptides, we first explored the use of H/D exchange mass spectrometry (HDX MS). Hereby, we found a reduction in proton exchange kinetics beyond the lactose-binding site. The measurement of fast HN/H2O exchange by phase-modulated NMR clean chemical exchange (CLEANEX) NMR on 15N-labeled Gal-1 then increased the spatial resolution to the level of individual amino acids. The mapped regions with increased protection from HN/H2O (D2O) exchange that include the reduction of solvent exposure around the interface can underlie the protein's compaction. These structural changes have potential to modulate this galectin's role in lattice formation on the cell surface and its interaction(s) with protein(s) at the F-face.

This work presents an in situ nanoscale structural characterization of a SrCl2-expanded natural graphite (ENG) composite during ammonia absorption and desorption using small-angle neutron scattering (SANS) together with X-ray powder diffraction and sorption measurements. For the processing of the composite material SANS patterns, we developed and implemented two methods, which showed comparable results. The study allowed following the evolution of the SrCl2 particles and the nanopores inside the particles during five sorption cycles. The structural changes were compared to the absorption and desorption kinetic measurements, allowing us to make qualitative analysis of the impact of the structural changes on the material properties, such as thermal conductivity and permeability. It was shown that the structural evolution of the composite material did not affect the desorption rate but significantly influenced the absorption rate after the first cycle. We also observed a significant improvement of the absorption kinetics due to the formation of nanopores in the fully deammoniated sample. In addition, the ENG matrix was shown to hinder the agglomeration of the SrCl2 particles during sorption processes, which is in contrast to literature findings reported for a nonsupported metal halide. The findings presented in this study can be of great interest in the research areas where SrCl2-ENG composites are widely studied, i.e., heat storage, heat pumps/refrigerators, deNOx removal, and solid-state ammonia storage.

We report a comprehensive study on the molecular conformation and dynamics of very large poly(ethylene oxide) rings in the melt: (i) for all rings, independent of the ring size, by small angle neutron scattering we observe a crossover from a strong Q-dependence at intermediate Q to a Q − 2 dependence at higher Q. Constructing a generic model including a crossover from Gaussian statistics at short distances to more compact structures at larger distances, we find the crossover at a distance along the ring of N e , 0 = 45 ± 2.5 monomers close to the entanglement distance in the linear counterpart. This finding is clear evidence for the predicted elementary loops building the ring conformation. (ii) The radius of gyration R g ( N ) follows quantitatively the result of numerous simulations. However, other than claimed, the crossover to mass fractal statistics does occur around N ≅ 10 N e , 0, but up to N ≅ 44 N e , 0, the relation R g ( N ) ∼ N 0.39 holds. The self-similar ring dynamics was accessed by pulsed field gradient-NMR and neutron spin echo spectroscopy: we find three dynamic regimes for center of mass diffusion starting (i) with a strong subdiffusive domain ⟨ r c o m 2 ( t ) ⟩ ∼ t α ( 0.4 ≤ α ≤ 0.65 ), (ii) a second subdiffusive region ⟨ r c o m 2 ( t ) ⟩ ∼ t 0.75 that (iii) finally, crosses over to Fickian diffusion. The internal dynamics at scales below the elementary loop size is well described by the ring Rouse motion. At larger scales, the dynamics is self-similar and follows very well the predictions of scaling models with a preference for the fractal loopy globule model. Finally, we note that the key results were previously published in the form of two letters [Kruteva et al., ACS Macro Lett. 9, 507–511 (2020) and Kruteva et al., Phys. Rev. Lett. 125, 238004 (2020)].

The results of Monte Carlo simulation and test reflectometry experiments on the “Gorizont” neutron reflectometer (on the IN-06 pulsed neutron source at INR RAS) after its upgrade with a two-dimensional detector with a positioning system are presented. The two-dimensional detector makes it possible to use the instrument not only for neutron reflectometry, but also for small angle neutron scattering. Estimates of the instrument resolution and the spectra of the neutron beam at different collimations have been obtained using Monte Carlo simulation. Test reflectometry experiments have been performed on mirrors with known characteristics. The characteristics match the manufacturer’s data with an error of 5%, obtained from the simulation.

A polymer brush system of a neutral polymer poly (ethylene glycol) with a molecular weight of Mw = 20 kDa on silicon substrates in an aqueous medium was studied by the specular neutron reflectometry. Structural changes in the density profile of a polymer brush caused by the interaction of polymer chains with micelles of the anionic surfactant dodecylbenzenesulfonate acid were observed. The effect is shown to be related to the formation of molecular polymer-micelle associates in the bulk of the solution, which was previously studied by small-angle neutron scattering in a wide range of surfactant concentrations at various molecular weights of the polymer. The density of the dry polymer layer on the silicon substrate was additionally characterized by X-ray reflectometry and scanning atomic force microscopy.

Competitive economic indicators for fast-neuron power reactors can be achieved with high coefficients of fuel burnout, which requires remarkable enhancement of radiation resistance of fuel pin claddings. Nowadays, low-activation vanadium alloys are projected as promising fuel cladding materials in view of their high radiation and thermal resistance in wide temperature and damage dose ranges. Neutron diffraction and small-angle neutron scattering are employed to study the microstructure of the V-4Ti-4Cr alloy subjected to irradiation with fast neutrons in the fluence range up to 1·1020 cm−2. Minor phases precipitated in the system are structurally characterized. The applicability and prospects of neutron diffraction methods in terms of studying the radiation behavior of this kind of alloys are shown.

Ceramides and diacylglycerols are groups of lipids capable of nucleating and stabilizing ordered lipid domains, structures that have been implicated in a range of biological processes. Previous studies have used fluorescence reporter molecules to explore the influence of ceramide acyl chain structure on sphingolipid-rich ordered phases. Here, we use small-angle neutron scattering (SANS) to examine the ability of ceramides and diacylglycerols to promote lipid domain formation in the well-characterized domain- forming mixture DPPC/DOPC/cholesterol. SANS is a powerful, probe-free technique for interrogating membrane heterogeneity, as it is differentially sensitive to hydrogen's stable isotopes protium and deuterium. Specifcally, neutron contrast is generated through selective deuteration of lipid species, thus enabling the detection of nanoscopic domains enriched in deuterated saturated lipids dispersed in a matrix of protiated un- saturated lipids. Using large unilamellar vesicles, we found that upon replacing 10 mol % DPPC with either C16:0 or C18:0 ceramide, or 16:0 diacylglycerol (dag), lipid domains persisted to higher temperatures. However, when DPPC was replaced with short chain (C6:0 or C12:0) or very long chain (C24:0) ceramides, or ceramides with unsaturated acyl chains of any length (C6:1(3), C6:1(5), C18:1, and C24:1), as well as C18:1-dag, lipid domains were destabilized, melting at lower temperatures than those in the DPPC/DOPC/cholesterol system. These results show how ceramide acyl chain length and unsaturation influence lipid domains, and have implications for how cell membranes might modify their function through the generation of different ceramide species.

International audience; Understanding the structure and dynamics of the bound polymer layer (BL) that forms on favorably interacting nanoparticles (NPs) is critical to revealing the mechanisms responsible for material property enhancements in polymer nanocomposites (PNCs). Here we use small angle neutron scattering to probe the temporal persistence of this BL in the canonical case of poly(2-vinylpyridine) (P2VP) mixed with silica NPs at two representative temperatures. We have observed almost no long-term reorganization at 150 °C (∼Tg,P2VP + 50 °C), but a notable reduction in the BL thickness at 175 °C. We believe that this apparently strong temperature dependence arises from the polyvalency of the binding of a single P2VP chain to a NP. Thus, while the adsorption–desorption process of a single segment is an activated process that occurs over a broad temperature range, the cooperative nature of requiring multiple segments to desorb converts this into a process that occurs over a seemingly narrow temperature range.

The rate of molecular exchange in diblock copolymer micelles is strongly dependent on the chain length of the core-forming insoluble block. Less is known about the influence of the soluble block forming the micellar corona. In this study we present a time-resolved small angle neutron scattering (TR-SANS) study exploring systematically the effect of corona chain length on the dynamics of chain exchange. As a model system we have taken amphiphilic AB diblock copolymers of the type C27H55-poly(ethylene oxide)x (C27–PEOx) with varying x between 4 and 36 kg/mol in aqueous solution in which well-defined spherical micelles with partially crystalline cores are formed. The TR-SANS results show that the chain exchange slows down considerably upon increasing PEO molecular weight, while the characteristic “attempt time” constant, τ0, was found to increase with a power law dependence τ0 ∼ MPEO9/5. The results are in excellent agreement with the Halperin and Alexander model1 and can be attributed to a reduced diffusion...

Using the electrostatic complex of G4 poly(amidoamine) (PAMAM) dendrimer with an amphiphilic surfactant as a model system, contrast variation small angle neutron scattering (SANS) is implemented to resolve the key structural characteristics of dendrimer-based guest–host system. Quantifications of the radial distributions of the scattering length density and the hydration level within the complex molecule reveal that the surfactant is embedded in the peripheral region of dendrimer and the steric crowding in this region increases the backfolding of the dendritic segments, thereby reducing the hydration level throughout the complex molecule. The insights into the spatial location of the guest molecules as well as the perturbations of dendrimer conformation and hydration level deduced here are crucial for the delicate design of dendrimer-based guest–host system for biomedical applications.

The morphology of Nafion (EW = 1000, Na+ form) in dilute solvents is investigated using small angle neutron scattering (SANS) and 19F NMR. SANS modeling indicates three types of particle morphology: (i) a well-defined cylindrical dispersion in glycerol and in ethylene glycol with different degrees of solvent penetration; (ii) a less-defined, highly solvated large particle (>200 nm) in water/isopropanol mixtures; and (iii) a random-coil conformation (true solution behavior) in N-methylpyrrolidone. These distinct morphological characteristics of Nafion are consistent with the main and side chain mobilities measured by 19F NMR.

The development of simple, efficient, and robust strategies affording the facile construction of biomimetic organocatalytic nano-objects is currently a subject of great interest. Herein, a new pathway to artificial organocatalysts based on partially collapsed individual soft nano-objects displaying useful and diverse biomimetic catalytic functions is reported. Single-chain polymer nanoparticles endowed with enzyme-mimetic activity synthesized following this new route display (i) a relatively extended morphology under good solvent conditions, as revealed by small angle neutron scattering and coarse-grained molecular dynamics simulation results, (ii) multiple, compartmentalized, and accessible catalytic sites in which borane catalytic units are retained via B···O interactions, and (iii) unprecedented reductase and polymerase enzyme-mimetic properties. © 2013 American Chemical Society., Financial support from the projects MAT2012-31088 (MINECO) and IT-654-13 (GV) is acknowledged. I. P.-B. acknowledges CSIC for her JAE-PREDOC grant. This work is based on has been supported by the European Commission under the 7th Framework Programme through the 'Research Infrastructures' action of the 'Capacities' Programme, NMI3-II Grant number 283883.

Structural evolution from poly(lactide) (PLA) macromonomer to resultant PLA molecular bottlebrush during ring opening metathesis polymerization (ROMP) was investigated for the first time by combining size exclusion chromatography (SEC), small-angle neutron scattering (SANS), and coarse-grained molecular dynamics (CG-MD) simulations. Multiple aliquots were collected at various reaction times during ROMP and subsequently analyzed by SEC and SANS. These complementary techniques enable the understanding of systematic changes in conversion, molecular weight and dispersity as well as structural details of PLA molecular bottlebrushes. CG-MD simulation not only predicts the experimental observations, but it also provides further insight into the analysis and interpretation of data obtained in SEC and SANS experiments. We find that PLA molecular bottlebrushes undergo three conformational transitions with increasing conversion (i.e., increasing the backbone length): (1) from an elongated to a globular shape due to longer side chain at low conversion, (2) from a globular to an elongated shape at intermediate conversion caused by excluded volume of PLA side chain, and (3) the saturation of contour length at high conversion due to chain transfer reactions.

Hydraulic fracturing of low-permeability rocks significantly enhances hydrocarbon production from unconventional reservoirs. However, fluid transport through low-permeability rocks and the influence of geochemical transformations on pore networks are poorly constrained. Mineral reactivity during interactions with injected water may alter the physical nature of the rock, which may affect hydrocarbon mobility. To assess alterations to the rock, we have previously conducted a hydrothermal experiment that reacted cubed rock samples (1 cm