Microemulsions as Reaction Media for the Synthesis of Mixed Oxide Nanoparticles: Relationships between Microemulsion Structure, Reactivity, and Nanoparticle Characteristics
Carolina Aubery, Conxita Solans, Sylvain Prevost, Michael Gradzielski, Margarita Sánchez Domínguez.Langmuir 29 2013 1779 - 1789 F. I. 4.186
Phase behavior, dynamics, and structure of W/O microemulsions of the system aqueous solution/Synperonic 13_6.5/1-hexanol/isooctane were studied, with the goal of determining their effect on Mn-Zn ferrite nanoparticle formation, kinetics and characteristics. Microemulsion structure and dynamics were studied systematically by conductivity, dynamic light scattering (DLS), differential scanning calorimetry (DSC), and small-angle neutron scattering (SANS). The main effect of cosurfactant 1-hexanol was a decrease in microemulsion regions as compared to the systems without cosurfactant; nevertheless, overlap of microemulsion regions in the systems with precursor salts (PS) and precipitating agent (PA) was achieved at lower S/O ratios, compared to the system without cosurfactant. At 50 °C, PA microemulsions are nonpercolated, while PS microemulsions are percolated. SANS indicates small prolate ellipsoidal micelles with the absence of free water up to 18 wt % PS solution; DSC studies confirm the absence of free water in this composition range. Kinetic studies show an increase in the reaction rate with increasing concentration of the aqueous solution; but the most significant effect in reaction kinetics was noted when cosurfactant was used, regardless of microemulsion dynamics and structure. On the other hand, the main difference regarding the characteristics of the obtained nanoparticles was observed when bicontinuous microemulsions were used as reaction media which resulted in 8 nm nanoparticles, versus a constant size of ~4 nm obtained with all other microemulsions regardless of aqueous solution content, dynamics, and presence or absence of cosurfactant. The latter effect of constant size is attributed to the fact that the water present is dominantly bound to the EO units of the surfactant.
Kinetic Study and Reaction Modeling of the High Temperature CO2 Capture by Na2ZrO3 Solid Sorbent
Diana Barraza Jiménez , Miguel A. Escobedo Bretado , Daniel Lardizábal Gutiérrez, Jesús M. Salinas Gutiérrez, Alejandro López Ortiz, Virginia Collins Martínez.International Journal of Hydrogen Energy 38 2013 2557-1564 F. I. 4.054
The use of high temperature solid CO2 capture in several fossil fuel-based energy production processes is an option to improve the efficiencies of such processes and simultaneously reduce the emission of greenhouse gases to the atmosphere. Recent studies in our laborator y  have shown the use of Na2ZrO3 as an alternate synthetic CO2 solid sorbent compared to expens ive lithium-base sorbents (Li2ZrO3 and Li4SiO4) [2,3] due to its excellent thermal stability, kinetics and CO2 capture capacity features. The objective of the pres ent work is to establish the CO2 sorption kinetics parameters such as: order of reaction, kinetic rate c onstant, apparent, intrinsic and diffusional activation energies and rate determining step to be used in a further design of a CO2 sorbent unit.
Enhanced spin pumping damping in yttrium iron garnet/Pt bilayers
Rezende, SM, Rodríguez-Suarez, RL; Soares, MM; Vilela-Leao, LH; Domínguez, DL; Azevedo, A.Applied Physics Letters 102 2013 DOI: 10.1063/1.4773993 F. I. 3.844
Detailed measurements of the magnetic relaxation expressed in the linewidth of the ferromagnetic resonance (FMR) absorption in thick films of yttrium iron garnet (YIG) and in YIG/Pt bilayers carried out at room temperature reveal a very large increase in the relaxation rate with the deposition of a Pt layer. The additional relaxation increases linearly with the microwave frequency characteristics of the spin pumping mechanism. The value of the spin mixing conductance obtained from the data is one order of magnitude larger than the largest possible value determined from measurements of the voltage generated by FMR spin-pumping.
Antimicrobial activity, cytotoxicity and inflammatory response of novel plastics embedded with silver nanoparticles
Fidel Martínez Gutiérrez, Jesús M Guajardo Pacheco, María E Noriega Treviño, Emily P Thi, Neil Reiner, Erasmo Orrantia, Yossef Av-Gay, Facundo Ruiz, Horacio Bach.Future Microbiology 8 2013 doi: 10.2217/fmb.13.5. F. I. 3.819
nfections associated with medical devices are an important cause of morbidity and mortality. Microorganisms are responsible for catheter infections that may then result in the local or systemic dissemination of the microorganism into the bloodstream. The aim of this study was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) embedded in polyurethane plastics, commonly used for catheter fabrication.
Effect of Water on the Stress Corrosion Cracking Behavior of API 5L-X52 Steel in E95 Blend
G.K. Pedraza Basulto, A.M. Arizmendi Morquecho, J.A. Cabral Miramontes, A. Borunda Terrazas, A. Martínez Villafañe, J.G. Chacón Nava.International Journal of Electrochemical Science 8 2013 5421 - 5437 F. I. 3.729
The effect of water content (0.5%, 1%, 2%,5%, 10% y 20 V%) in E95 blend (5V% gasoline–95V%ethanol) on the stress corrosion cracking (SCC) susceptibility of X-52 carbon steel was investigated. Slow strain rate tests (SSRT) coupled with electrochemical noise measurements (ECN) were carried out using a strain rate of 1 X 10-6s-1. In general, scanning electron microscopy (SEM) observations on fracture surfaces showed a ductile behavior. However, secondary cracking was only observed for specimens exposed to solution containing up to 2V% water. ECN gave indication of a likely localized corrosion process occurring at low water concentrations, whereas for water content above 2V%, a uniform corrosion process seems more likely to occur. In addition, the material response immersed into the various solutions was investigated by using linear polarization resistance (LPR) measurements, weight loss and pH measurements.Reasons to explain the behavior found are discussed.