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Flocculation process was studied in emulsions formulated with 10 wt.% sunflower oil, 2, 5 or 7.5 wt.% NaCas, and with or without addition of sucrose (0, 5, 10, 15, 20 or 30 wt.%). Two different processing conditions were used to prepare emulsions: ultraturrax homogenization or further homogenization by ultrasound. Emulsions with droplets with diameters above (coarse) or below (fine) 1 μm were obtained. Emulsions were analyzed for droplet size distribution by static light scattering (SLS), stability by Turbiscan, and structure by confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). SAXS data were fitted by a theoretical model that considered a system composed of poly dispersed spheres with repulsive interaction and presence of aggregates. Flocculation behavior was caused by the self-assembly properties of NaCas, but the process was more closely related to interfacial protein content than micelles concentration in the aqueous phase. The results indicated that casein aggregation was strongly affected by disaccharide addition, hydrophobic interaction of the emulsion droplets, and interactions among interfacial protein molecules. The structural changes detected in the protein micelles in different environments allowed understanding the macroscopic physical behavior observed in concentrated NaCas emulsions. [ABSTRACT FROM AUTHOR]

Abstract: The physicochemical properties of emulsions play an important role in food systems as they directly contribute to texture, sensory and nutritional properties of foods. Sodium caseinate (NaCas) is a well-used ingredient because of its good solubility and emulsifying properties and its stability during heating. One of most significant aspects of any food emulsion is its stability. Among the methods used to study emulsion stability it may be mentioned visual observation, ultrasound profiling, microscopy, droplet size distribution, small deformation rheometry, measurement of surface concentration to characterize adsorbed protein at the interface, nuclear magnetic resonance, confocal microscopy, diffusing wave spectroscopy, and turbiscan. They have advantages and disadvantages and provide different insights into the destabilization mechanisms. Related to stability, the aspects more deeply investigated were the amount of NaCas used to prepare the emulsion, and specially the oil-to-protein ratio, the mobility of oil droplets and the interactions among emulsion components at the interface. It is known that the amount of protein required to stabilize oil-in-water emulsions depends, not only on the structure of protein at the interface, and the average diameters of the emulsion droplets, but also on the type of oils and the composition of the aqueous phase. Several authors have investigated the effect of a thickening agent or of a surface active molecule. Factors such as pH, temperature, and processing conditions during emulsion preparation are also very relevant to stability. There is a general agreement among authors that the most stable systems are obtained for conditions that produce size reduction of the droplets, an increase in viscosity of the continuous phase and structural changes in emulsions such as gelation. All these conditions decrease the molecular mobility and slow down phase separation. [Copyright &y& Elsevier]

Abstract: Many food products such as ice cream, yoghurt, and mayonnaise are some examples of emulsion-based food. The physicochemical properties of emulsions play an important role in food systems as they directly contribute to texture, sensory and nutritional properties of food. One of the main properties is stability which refers to the ability of an emulsion to resist physical changes over time. The aim of the present work was to analyze the effect of processing conditions and composition on sodium caseinate (NaCas) emulsions stability. The main destabilization mechanisms were identified and quantified. The relationship between them and the factors that influence them were also investigated. Emulsions stabilized with NaCas were prepared using an ultrasound liquid processor or a high pressure homogenizer. Stability of emulsions was followed by a Turbiscan (TMA 2000) which allows the optical characterization of any type of dispersion. The physical evolution of this process is followed without disturbing the original system and with good accuracy and reproducibility. To further describe systems, droplet size distribution was analyzed with light scattering equipment. The main mechanism of destabilization in a given formulation depended on different factors such as NaCas concentration, droplet size or processing conditions. The rate of destabilization was markedly lower with addition of sugar or a hydrocolloid to the aqueous phase. Xanthan (XG) and locust bean (LBG) gums produced an increase in viscosity of the continuous phase and structural changes in emulsions such as gelation. Sugars interacted with the protein decreasing particle size and increasing emulsion stability. The stability of caseinate emulsions was strongly affected not only by the oil-to-protein ratio but also by processing conditions and composition of aqueous phase. The structure of the protein and the interactions protein–sugar or the presence of a hydrocolloid played a key role in creaming and flocculation processes of these emulsions. [Copyright &y& Elsevier]

• Magnetic iron oxide nanoparticles were immobilized inside electrospun PVA nanofibers. • High arsenate adsorption capacity is achieved. • Magnetic analysis showed the confinement and well dispersion of MIONs in nanofibers. • SAXS/WAXS techniques permitted macroscopic analysis of PVA-MIONs. • Adsorption process occurs in three steps: swelling, adsorption and equilibrium. Superparamagnetic iron oxide nanoparticles (SPIONs) are great adsorbents of toxic arsenic in water. However, SPIONs efficiency is limited by a tendency towards agglomeration, and an extra filtering process is required in actual applications to avoid possible harmful effects of nanoparticles released to the environment. Here, we show a novel green method to confine and disperse SPIONs (10 nm) inside insoluble electrospun PVA nanofibers (final concentration 0.14 wt. %). We found that the resulting membrane has an enhanced arsenic adsorption capacity (> 52 mg/g) and presents a new adsorption mechanism, involving a high swelling of the superhydrophilic nanofibers before actual solution interchange can occur. A suitable heat treatment provided water insolubility to the membrane while maintaining hydrophilicity and active sites in the SPIONs. We show the excellent dispersion and homogeneous distribution of the SPIONs inside the nanofibers using electron microscopies and scale this analysis to an area of statistical significance via magnetic studies and novel Small and Wide Angle X-Ray Scattering SAXS/WAXS 2D scannings. The production process is environmentally friendly, given that only PVA was used as SPIONs dispersant and no chemicals were added for crosslinking. This work presents a novel material that expands the broad technological applications of both iron oxide nanoparticles and electrospinning, opening a route to new horizons in water purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyesterification transformed non-mesogenic triphenylenes into liquid crystals. • Their key molecular feature is carboxyl connectors distant from triphenylene core. • This unusual polyester structure yielded room temperature discotic nematic phases. • Thermal homeotropic self-alignment of polymers on diverse single-substrates. • Molecular control on the kind of liquid crystal phase and on alignment ability. We present the synthesis, characterization, and study of Liquid Crystal properties of a new series of polyesters containing 2,7-di-functionalized triphenylene units in the main chain, whose distinctive feature is that the carboxyl moiety is distant from the aromatic core. Several molecular aspects, such as the distance between the carboxylic group to the core, the length of the connector, and the orientation of the carboxyls were analyzed. In addition, we have investigated the influence of these molecular parameters on the thermal self-alignment of the polymers on different substrates. We have found a simple method to obtain a monodomain homeotropic orientation of these polyesters on a single substrate. [ABSTRACT FROM AUTHOR]

In this work, we analyze Sm 2 O 3 -doped CeO 2 (SDC) nanopowders and NiO/SDC nanocomposites in terms of sample reducibility and catalytic activity for partial oxidation of methane. We assess the role of the average crystallite size and specific surface area in Ni and Ce reduction kinetics by in-situ X-ray absorption spectroscopy experiments in diluted H 2 and CH 4 /O 2 mixtures. Our results indicate that crystallite size and surface area play a key role in CH 4 activation through modification of the sample redox behavior. The oxidation of the metallic phase is the main cause of sample deactivation. A clear relationship is established between the temperature of maximum Ni oxidation rate and grain size. An interplay between Ce atoms from the support and Ni from the active phase was observed during the experiments, evidencing a complex relationship between oxygen vacancy concentration and catalytic activity. A high Ce3+ content in catalyst support was detrimental to catalytic activity [Display omitted] • Redox behavior significantly depends on grain size and surface area. • Sample deactivation occurs due to re-oxidation of metallic phase. • Temperature of maximum rate of Ni oxidation is directly correlated to grain size. • Ce reduction is enhanced by H 2 spillover mechanism over metallic Ni particle • An excessive concentration of oxygen vacancies is detrimental to catalytic activity. [ABSTRACT FROM AUTHOR]

• Hydrothermally synthesized NaNbO 3 as a promising CO 2 conversion photocatalyst. • Silver decoration allows tuning product selectivity from CO to CH 3 OH. • Surface chemistry and electronic modifications drive selectivity in Ag/NaNbO 3. • APXPS of CO 2 photoreduction on such catalysts is reported for the first time. The hydrothermal synthesis of the perovskites NaNbO 3 , NaTaO 3 and the intermediate composition NaNb 0.5 Ta 0.5 O 3 , as CO 2 conversion photocatalysts is reported. Among them, the niobate shows the most promising performance under UV irradiation not only in terms of conversion and light utilization ability, but also regarding the selectivity towards CO 2 reduction against hydrogen evolution from water protons. Further modification of NaNbO 3 with silver as co-catalyst results in an increase of the selectivity towards highly reduced products, primarily methanol, against the carbon monoxide production mainly observed with the bare semiconductor. A thorough structural, electronic, electrochemical characterization, together with in-situ surface analysis by APXPS, was undertaken to gain deeper insight into the reasons that account for such changes. On the one hand, for the bare semiconductors, increased light absorption and the sole presence of Nb in +4 state at the surface seem to drive the superior activity of NaNbO 3. On the other hand, electronic and surface chemistry modifications induced by 0.1 wt.% silver deposition are proposed to govern the higher selectivity towards methanol. Excessive metal loading, in turn, enhances the selectivity effect but at the expense of conversion, in such a way that light utilization becomes poorer than with the bare niobate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Emulsion polymerization techniques enabled to prepare amphiphilic nanoparticles. • Several techniques were used to demonstrate the multi-hierarchical architecture. • Hydrophobic domains preferentially accumulate toward the core of the nanoparticles. • Post-synthetic modification is achieved and the architecture remained the same. • Smaller nanoparticles seem to more effectively bring a cargo molecule into the skin. Nanoparticles (NPs) with functional cores are gaining research interest due to their advanced architecture. However, exposed reactive groups on NP surfaces can lead to material side reactions and biomedical tissue damage. NPs with multi-hierarchical morphologies can be synthesized by various methods; however, controlling the size and position of the functional groups using conventional and scalable methods is still a challenge. This study explores emulsion-based polymerization methods for producing multi-hierarchical NPs with varying sizes and compositions. We compared micro-, macro-, and semi-batch emulsion polymerization using 2-hydroxyethyl methacrylate (HEMA) and pentafluorophenyl methacrylate (PFMA) as co-monomers. The components present in PFMA can be substituted and are used for post-synthetic functionalization. The results suggest that the architecture of the synthesized NPs is multi-hierarchical, with the substitutable pentafluorophenyl units surrounded by HEMA monomers. Additionally, we evaluated the NPs' ability to enhance dermal drug penetration using nile red as a hydrophobic drug model. Significant variations in skin permeation enhancement properties were observed among the NPs, underscoring the impact of the synthesis method on nanocarriers' drug delivery performance. [ABSTRACT FROM AUTHOR]

We have studied for the first time the relevant features of the thermally activated nanostructural transformations occurring in a material initially consisting of a flat Si(001) wafer in which a nanoporous Ni-doped silica film is deposited. Two simultaneous transformation processes occur, and both were investigated by in situ grazing-incidence small-angle X-ray scattering during isothermal annealing at 405 °C, namely the kinetics of formation of (i) oriented NiSi 2 hexagonal nanoplates endotaxially buried in a Si(001) wafer, and (ii) a set of randomly oriented spherical Ni nanocrystals with a two-mode radius distribution embedded in a Ni-doped silica thin film deposited on the Si wafer and in an intermediate layer between SiO 2 film and the layer in which NiSi 2 nanoplates are embedded. The analyses of the successive 2D scattering patterns measured in situ during isothermal annealing led us to establish the time invariances of the average radii of the spherical Ni nanocrystals and the time dependence of their number, together with the time dependences of the maximum diameter, thickness, number and total volume of the hexagonal NiSi 2 nanoplates buried in the Si wafer. [Display omitted] [ABSTRACT FROM AUTHOR]