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[en] Experimental data and results of theoretical studies dealing with the synthesis of nanoparticles by the condensation of products of chemical reactions in reverse microemulsions are generalized. Attention is focused on the analysis of mechanisms of nanoparticle nucleation and growth. The bibliography includes 252 references.
[en] The concentration fluorescence quenching of cyanine dyes in micellar solutions and microemulsions is studied. The concentration quenching by dimers and statistical traps is analyzed. 14 refs., 4 figs., 1 tab
[en] This report describes some preliminary phase behavior studies and phase inversion temperature measurements in seawater, bunker oil and dispersant. The objectives have been to find new ways of characterizing dispersants for dispersing oil spill at sea and, perhaps, to throw new lights on the mechanism of dispersion formation (oil-in-water emulsification). The work has been focussed on the relation to phase behavior and the existence of microemulsion in equilibrium with excess oil and water phases. The dispersing process is also compared to the recommended conditions for emulsion formation. When forming an oil-in-water emulsion in an industrial process, it is recommended to choose an emulsifier which gives a phase inversion temperature (PIT) which is 20 - 60oC higher than the actual temperature for use. The emulsification process must take place close to the PIT which is the temperature at which the emulsion change from oil-in-water emulsion to water-in-oil emulsion when the system is stirred. This condition corresponds to the temperature where the phase behavior change character. The purpose has been to find out if the composition of the dispersants corresponds to the recommendations for oil-in-water emulsification. The amount of experimental work has been limited. Two kinds of experiments have been carried out. Phase behavior studies have been done for seawater, bunker oil and four different dispersants where one had an optimal composition. The phase behavior was hard to interpret and is not recommended for standard dispersants test. The other experimental technique was PIT-measurements by conductivity measurements versus temperature. 4 figs., 1 tab., 4 refs
[en] Theoretical and experimental studies on highly concentrated emulsions are critically analysed. The views on the relationship between the stability of surfactant-stabilised emulsions and the properties of microemulsion phases formed in surfactant-water-oil ternary systems are considered. The empirical criteria and rules that can be used to predict the type and stability of emulsions are presented. The physicochemical factors determining the rupture stability of emulsion films are discussed.
[en] Micelle and reverse micelle microemulsions can be favourably utilized in producing nano sized particles. The paper reports a general description of microemulsions systems, as well as their application in materials synthesis. By using one of the described methods, nano structured manganese ferrite, to be utilized in hydrogen production. was synthesized and the produced material was characterized in terms of morphological, microstructure and thermal properties
[it]Micelle e micelle inverse in microemulsione possono essere utilizzate nella produzione di particelle di dimensione nanometrica. Il presente lavoro descrive i sistemi in microemulsione e la loro applicabilita nella sintesi dei materiali. Mediante uno dei metodi descritti e stata sintetizzata ferrite di manganese nanostrutturata, da utilizzare nella termoproduzione di idrogeno, e il materiale prodotto e stato caratterizzato in termini di proprieta morfologiche, microstrutturali e termiche
[en] The process of miniemulsification allows the generation of small, homogeneous, and stable droplets containing monomer or polymer precursors and magnetite which are then transferred by polymer reactions to the final polymer latexes, keeping their particular identity without serious exchange kinetics involved. It is shown that the miniemulsion process can excellently be used for the formulation of polymer-coated magnetic nanoparticles which can further be used for biomedical applications. The use of high shear, appropriate surfactants, and the addition of a hydrophobe in order to suppress the influence of Ostwald ripening are key factors for the formation of the small and stable droplets in miniemulsion and will be discussed. Two different approaches based on miniemulsion processes for the encapsulation of magnetite into polymer particles will be presented in detail
[en] Complete text of publication follows. The present communication is focused on the synthesis of polymer nanoparticles (NPs) capable of binding to specific biomolecules such as non-steroidal anti-inflammatory drugs (NSAIDs). Within this important group we selected Naproxen, one of the 2-arylpropionic acids (profens), due to its use for the reduction of moderate to severe. We have developed inexpensive and selective nanoparticles under mild conditions of inverse microemulsion polymerization using aqueous acrylamide as monomer and N-N'methylenebisacrylamide as cross-linker, employing the surfactants polyoxyethylene-4-lauryl ether (BrijR30) and sodium bis(2-ethylhexyl)- sulfosuccinate in hexane. We incorporated into the nanoparticles a selective fluorescent monomer, (E)-4-(4-(dimethylamino)styryl)-1-(4(methacryloyloxymethyl)benzyl) pyridinium chloride (mDMASP) which shows, inside the nanoparticles, a broad absorbance at around 460 nm and fluorescence emission at around 590 nm when suspended in phosphate buffer of pH 7.2. The acrylamide nanoparticles exhibited a diameter in the range of 50-100 nm. The analyte recognition is based on an increase in fluorescence at 590 nm upon addition of different concentrations of Naproxen. In order to evaluate the selectivity of the nanoparticles for the intended application to water analysis, a systematic study was conducted on the effect produced by common species that can interfere in the determination of Naproxen, demonstrating the selectivity of this method. Thus, we propose a new method for the determination of Naproxen that can be used for different analytical applications, considering the simplicity of the procedure. We thankfully acknowledge the financial support from the EU Transfer of Knowledge project 'Sensor Nanoparticles for Ions and Biomolecules' (MTKD-CT-2005-029554) and the EU Research Training Network 'Nanomaterials for Application in Sensors, Catalysis and Emerging technologies' (MRTN-CT-2006-033873).
[en] Four series nanocrystalline ferrites with nominal composition, NiZr x Co x Fe2−2 x O4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8) Ni0.5Sn0.5Co x Mn x Fe2−2 x O4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8), Mg1− x Ca x Ni y Fe2− y O4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8; y = 0, 04, 0.8, 1.2, 1.6) and Mg1− x Ni x Co y Fe2− y O4 ( x,y = 0.0, 0.2, 0.4, 0.6, 0.8) have been fabricated using the microemulsion synthesis route. The synthesized materials are investigated for dc electrical resistivity measurements. The variation of dc electrical resistivity of these materials has been explainedon the basis of hopping mechanism of both holes and electrons. (paper)