Lopez-Dominguez V.,University of Barcelona |
Hernaindez J.M.,University of Barcelona |
Tejada J.,University of Barcelona |
Ziolo R.F.,Research Center en Quimica Aplicada
Chemistry of Materials | Year: 2013
In this work, we show the enormous size effect on the ordering transition temperature, TO, in samples of CoFe2O4 nanoparticles with diameters ranging from 1 to 9 nm. Samples were characterized by HRTEM and XRD analyses and show a bimodal particle size distribution centered at 3 nm and around 6 nm for "small" and "large" particles, respectively. The results and concomitant interpretation were derived from studies of the magnetization dependence of the samples on temperature at low and high magnetic fields and relaxation times using both dc and ac fields. The large particles show a typical superparamagnetic behavior with blocking temperatures, TB, around 100 K and a Curie temperature, T C, above room temperature. The small particles, however, show a colossal reduction of their magnetic ordering temperature and display paramagnetic behavior down to ∼10 K. At lower temperatures, these small particles are blocked and show both exchange and anisotropy field values above 5 T. The order of magnitude reduction in TO demonstrates a heretofore unreported magnetic behavior for ultrasmall nanoparticles of CoFe 2O4, suggesting its further study as an advanced material. © 2012 American Chemical Society.
Sanchez-Valdes S.,Research Center en Quimica Aplicada
Polymer Bulletin | Year: 2014
Silver nanoparticles were deposited on the surface of an extruded film of linear low density polyethylene/cyclo olefin copolymer (LLDPE/COC) blend by an ultrasound-assisted method. A series of LLDPE/COC/silver nanocomposites, containing 0.02, 0.05, 0.08 and 0.1 mol/L of AgNO3 were prepared and characterized. The effect of ultrasound method on the silver deposition on the film surface was characterized as well as the effect of silver nanoparticles on their fungicidal characteristics. The silver action and biocide effect of the films were enhanced significantly as the silver content increased from 0.02 to 0.08 mol/L of AgNO3 and after that no significant enhancement was observed. From the UV-Vis analysis and transmission electron microscopic observations, the particle shape, size and size distribution were determined. Films of LLDPE/COC blends with silver deposition exhibited a noticeable increase in water vapor barrier properties with the increase in the concentration of AgNO3 and demonstrated good fungicidal activity, specifically against fungus Aspergillius niger. The observed results could be applied in the design of industrial films for packaging. © 2014 Springer-Verlag Berlin Heidelberg.
Research Center En Quimica Aplicada | Date: 2013-08-21
A method for producing drug-loaded polymeric nanoparticles, which includes the steps of: (a) preparing a first solution by dissolving a drug in a polymerizable monomer; (b) preparing a micellar solution by dissolving a surfactant and a water-soluble radical initiator in water; (c) adding said first solution to said micellar solution for polymerizing said polymerizable monomer, obtaining a dispersion of drug-loaded polymeric nanoparticles, the drug-loaded polymeric nanoparticles have a controlled size with average diameter smaller than 50 nm; and (d) evaporating residual polymerizable monomer from the dispersion of drug-loaded polymeric nanoparticles.
Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: NMP.2010.1.2-4 | Award Amount: 4.04M | Year: 2010
Silver nanoparticles and silver based nanostructured composites are being frequently used in a variety of biomedical and industrial applications, such as an antimicrobial agents, lead-free solders, electric contact materials, gas-sensitive sensor, etc. The most complicated Silver using problems are related to: i) recovery of silver from ore waste materials; ii) the controlled synthesis of metal nanoparticles of well-defined size, shape and composition; iii) nanoparticles incorporation to desired implant surfaces; iv) synthesis of Silver based nanostructured composites for industrial purposes. The main goal of the Project is to develop: 1. Clean and efficient procedure of silver recovery from waste: Combined Mechanical Activation Thermal Oxidation Processing jarosite type residues to alleviate and accelerate the following precious metal leaching; 2. Combined nanotechnology of biological synthesis (use of plants for the nanoparticles synthesis) of Ag nanoparticles and its deposition on implant surfaces by electrophoretic and plasma spraying deposition; 3. Nanostructuring technology of Silver based nanocomposites manufacturing for electrical contact applications. Pilot production and trials of developed Ag nanoparticle modified implants and Ag based nanostructured composites: 1. TiO2 and Hydroxyapatite Ca10(PO4)6(OH)2) coated implants which are widely used in orthopaedic surgery because of their good biocompatibility related to the osteoconductive properties of calcium phosphate coating; 2. Ag-SnO contacts for electrical systems; these composites combine high resistance to welding and to electric arch erosion of the refractory phases with the high electric and thermal conductivities.
Research Center En Quimica Aplicada, Instituto Nacional de Investigaciones Nucleares and Research Center Cientifica Of Yucatan | Date: 2013-07-03
A method for obtaining sweet gas, synthetic gas, and sulphur from natural gas. The method includes the steps of removing impurities from the natural gas for obtaining pre-treated natural gas; sweetening the pre-treated natural gas through a separation using a plurality of membranes for obtaining sweet gas and acid gases; ionizing the acid gases to dissociate them into sulphur and synthetic gas with remnants of acid gases; and neutralizing the synthetic gas with remnants of acid gases for generating sweet gas. Likewise, a system is presented on how to implement the method.