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In this work, the nanostructure of oxide dispersion-strengthened steels was studied by small-angle neutron scattering (SANS), transmission electron microscopy (TEM), and atom probe tomography (APT). The steels under study have different alloying systems differing in their contents of Cr, V, Ti, Al, and Zr. The methods of local analysis of TEM and APT revealed a significant number of nanosized oxide particles and clusters. Their sizes, number densities, and compositions were determined. A calculation of hardness from SANS data collected without an external magnetic field, or under a 1.1 T field, showed good agreement with the microhardness of the materials. The importance of taking into account two types of inclusions (oxides and clusters) and both nuclear and magnetic scattering was shown by the analysis of the scattering data. [ABSTRACT FROM AUTHOR]

In this work, the synthesis of ordered mesoporous silica of MCM-41 type was investigated aimed at improving its morphology by varying the synthesis conditions in a one-pot process, employing different temperatures and solvent conditions. 2-methoxyethanol was used as co-solvent to ethanol. The co-solvent ratio and the synthesis temperature were varied. The pore morphology of the materials was characterized by nitrogen porosimetry and small angle neutron scattering (SANS), and the particle morphology by transmission electron microscopy (TEM) and ultra-small angle neutron scattering (USANS). The thermal behavior was investigated by simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC) measurements. The SANS and N2 sorption results demonstrated that a well-ordered mesoporous structure was obtained at all conditions in the synthesis at room temperature. Addition of methoxyethanol led to an increase of the pore wall thickness. Simultaneously, an increase of methoxyethanol content led to lowering of the mean particle size from 300 to 230 nm, according to the ultra-small angle scattering data. The ordered porosity and high specific surfaces make these materials suitable for applications such as adsorbents in environmental remediation. Batch adsorption measurements of metal ion removal from aqueous solutions of Cu(II) and Pb(II) showed that the materials exhibit dominantly monolayer surface adsorption characteristics. The adsorption capacities were 9.7 mg/g for Cu(II) and 18.8 mg/g for Pb(II) at pH 5, making these materials competitive in performance to various composite materials. [ABSTRACT FROM AUTHOR]

Mesoporous silica particles have been prepared with functionalized precursors, used either in situ co-condensation process or as post-synthesis grafting agents, in order to deliver surface functionalisation. Aminopropyl, mercaptopropyl, vinyl and hexyl organosilanes were used as funtionalized precursors, tetraethyl orthosilicate as the base silica precursor material, hexadecyl-trimethylammonium bromide (CTAB) as directing agent and water-ethanol mixture as solvent, with ammonia catalyst. The aim was to explore the effect of various recipes on the structural properties of the composite materials. The samples' microstructures have been evaluated using nitrogen sorption and small angle neutron scattering. Ordered mesoporous structures were obtained, for almost all synthesis conditions, after the solvent-extraction of the template agent. Only in one case, for the materials functionalized by mercaptopropyl groups in co-condensation route, disordered amorphous structure was obtained. All samples functionalized by post-grafting presented well-ordered mesoporous structures. The results have potential use for easy design of sorbent materials for drug loading or pollutant adsorption applications. [ABSTRACT FROM AUTHOR]

A series of calibration measurements have been performed on Suanni – the first small‐angle neutron scattering spectrometer entering into routine user operation in China – aiming to characterize instrument performance and to provide a reference for user experiments. Various calibration standards were used to verify the precise association of the scattering intensity I with the scattering vector magnitude q at short and medium sample–detector distances. The measurements recorded for silver behenate powder revealed a slight shift of the neutron wavelength (λ) at the sample position as compared to the nominal λ calculated by the selector constant. The deviation was more significant with λ > 0.8 nm owing to the shape of the incoming neutron spectrum incident on the selector. The measured dead time for the entire detection system is 2.7 µs, as determined by measurements with varying fluxes. A protonated/deuterated polystyrene blend was employed as the primary standard to calibrate the secondary standard H2O. The instrument covers an effective q range between 0.013 and 5 nm−1, as demonstrated by scattering curves obtained from a monodisperse poly(methyl methacrylate) nanoparticle suspension and a glassy carbon plate. The wavelength, the scattering vector magnitude and the absolute intensity for the Suanni small‐angle neutron scattering spectrometer have been calibrated by using standard samples, providing an informative reference for users and diagnostic tools for instrument scientists. [ABSTRACT FROM AUTHOR]

The microstructure of compression molded Estane 5703 films exposed to 11%, 45%, and 80% relative humidity and 70 °C for 1 and 2 months has been studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Scattering data indicated increase of the interdomain distance and domain size with a higher humidity and longer aging time. GPC data showed a progressive shortening of polyurethane chains with increasing humidity and aging time. The shortening of the polyurethane chains caused a drop of the glass transition temperature of soft segments, and promoted crystallization of the soft segments during long-time storage of the aged samples at room temperature. FTIR showed a substantial increase in the number of inter-urethane H-bonds in the aged samples. This correlates with the increase of the hard domain size and the degree of phase separation as measured by SANS. The data collected reveals that the reduced steric hindrance caused by hydrolysis of ester links in polybutylene adipate residues promotes the organization of hard segments into domains, leading to the increase of domain size and distance, as well as phase segregation in aged Estane. These findings provide insight into the effects of humidity and thermal aging on the microstructure of aged polyester urethane from molecular to nanoscale level. [ABSTRACT FROM AUTHOR]

The gamma irradiation induced aging of thermoplastic polymer Estane 5703 in air and water environments was studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and X-ray diffraction (XRD). The degree of phase mixing was increased after irradiation, accompanied by the increase of domain distance and decrease of domain size. The hard domain distance increased from 9.8 to 11.2 nm and 14.4 nm for the samples irradiated in air and water with a dose up to 500 kGy, respectively. The GPC results indicated progressive formation of larger linked structures with very high molar mass with increasing absorbed doses. The samples irradiated in water exhibited a stronger aging effect than those irradiated in air. The FTIR results suggested that the cross-linking occurred among the secondary alkyl radicals, and the interactions in hard domains weakened because of the loss of inter-urethane H-bonds. The volume fraction of well-ordered soft segments in Estane increased upon irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Intermolecular interactions between a single water and two N,N′-dimethylethyleneurea (DMEU) molecules have been investigated using ab initio quantum chemistry method. The local and density-fitting approximations of the standard Møller–Plesset perturbation theory (DF-LMP2) have been employed together with the aug-cc-pVTZ basis set. Several trimeric systems were built where the water molecule, through the O–H⋯N hydrogen bond interactions, played the role of the bridge between the two DMEU molecules. The results show that the presence of the water molecule does not increase the stability of the trimeric systems. In the first three configurations the water molecule intercalates between two DMEU molecules, forming stable clusters. In the next three configurations, the water molecule is attached to a plane-parallel stacked DMEU dimer through the C=O⋯H–O hydrogen bond, and these structures are more stable than the first three. Small-angle neutron scattering data show clustering of DMEU molecules in their dilute aqueous solutions, and the ab initio results suggest that DMEU molecules could form contact pairs in dilute aqueous solutions. [Copyright &y& Elsevier]

Organic-inorganic silica composites have been prepared via acid catalyzed sol-gel route using tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) as silica precursors and n-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]) as co-solvent and pore template, by varying the content of the ionic liquid (IL). Morphology of the xerogels prepared using the ionic liquid templating agent were investigated using scanning electron microscopy and small angle neutron scattering (SANS). Thermal analysis has been used in order to evaluate the thermal and structural stability of the materials, in both nitrogen and synthetic air atmosphere. In nitrogen atmosphere, the IL decomposition took place in one step starting above 150 °C and completed in the 150–460 °C temperature interval. In synthetic air atmosphere, the IL decomposition produced two-step mass loss, mainly in the 170–430 °C temperature interval. The decomposition mechanism of the IL inside the silica matrix was studied by mass spectrometric evolved gas analysis (MSEGA). The measurements showed that the degradation of the IL's longer side chain (butyl) starts at low temperature (above 150 °C) through a C-N bond cleavage, initiated by the nucleophilic attack of a fluorine ion. [ABSTRACT FROM AUTHOR]

We report on the structural evaluation of high fat fish oil-in-water emulsions emulsified with sodium caseinate (CAS) and phosphatidylcholine (PC). The microemulsions contained 70% (w/w) fish oil with 1.05–1.4% (w/w) CAS and 0.4–1.75% (w/w) PC and were studied by the combination of light scattering together with small-angle X-ray and neutron scattering (SAXS/SANS). Aqueous CAS forms aggregates having a denser core of about 100 kDa and less dense shell about 400 kDa with the hard sphere diameter of 20.4 nm. PC appears as multilayers whose coherence length spans from 40 to 100 nm. PC monolayer separates oil and water phases. Moreover, 80% CAS particles are loosely bound to the interface but are not forming continuous coverage. The distance between aggregated CAS particles in microemulsion is increased compared to CAS aggregates in pure CAS-in-water system. PC multilayers become larger in the presence of oil-water interface compared to the pure PC mixtures. Bilayers become larger with increasing PC concentration. This study forms a structural base for the combination of CAS and PC emulsifiers forming a well-defined thin and dense PC layer together with thick but less dense CAS layer, which is assumed to explain its better oxidative stability compared to single emulsifiers. [ABSTRACT FROM AUTHOR]

Highlights: [•] The stable nanostructured lipid carrier was designed and prepared by HPH. [•] DLS, TEM, SANS, SAXS and XRD were used to study the physicochemical properties. [•] Docetaxel was used as an API to study the effects of lipophilic drug on NLC. [•] SANS was firstly used to study the microstructure of NLC for release properties. [Copyright &y& Elsevier]

We have investigated magnetic properties for reactor pressure vessel model alloys with variable Cu contents, subjected to neutron irradiation up to a fluence of 9 × 10 19 n cm − 2. Unlike a monotonic increase of microhardness with neutron fluence, the major-loop coercivity decreases at a higher fluence and the decrease becomes larger for the alloy containing a higher amount of Cu. The measurements of first-order reversal curves (FORCs) for the high-Cu alloy show that the position of the FORC distribution peak shifts toward a lower coercivity just after neutron irradiation, followed by a slight increase, associated with the broadening along both the coercivity and interaction field axes. The results can be explained by the enhancement of magnetic inhomogeneity in a matrix due to Cu precipitation and an increasing magnetostatic interaction between local magnetic regions with different coercivity. The magnetic method using FORCs can be a possible technique which provides in-depth information on microstructural changes due to neutron irradiation, which is not obtained by measurements of a conventional major hysteresis loop. [ABSTRACT FROM AUTHOR]