Electrodeposited metal matrix nanocomposites as thin films and high aspect ratio microstructures for MEMS

The electrodeposition of metal-matrix nanocomposites as thin film and high aspect ratio microstructures (HARM’s) for MicroElectroMechanical Systems (MEMS) components is examined. The effect of -Al2O3 nanopowder on copper reduction from acidic and basic electrolytes is examined with rotating disk electrodes (RDE’s). At pH 0.2, regions of copper inhibition and enhancement are identified in the kinetic regime. Low particle loading (12.5 g/L) results in an inhibited copper rate, while, high particle concentration (60 g/L) does both, inhibits the rate at low overpotentials and accelerates it at higher overpotentials, depending on the electrode rotation rate. At pH 8 the presence of particles resulted in an enhancement of the Cu reaction rate, while at pH 10 the reaction rate appeared inhibited. The change of the Cu partial current density was attributed to the change of copper complexed species. A mathematical model that couples particle mass transport with metal kinetics during Cu--Al2O3 electrodeposition from acidic electrolytes was developed. The model, based on convective-diffusion transport and Tafel reaction kinetics, is solved numerically, and the calculated species concentrations at the solution-electrode interface are used to describe the electrode processes. The simulation was in agreement with experimental observations, predicting the influence of experimental variables. A comparison of Cu-particle nanocomposites electrodeposition into deep recesses from sulfuric acid and ammonia-citrate electrolytes is presented, to provide better understanding of how complexing agents affect the copper-alumina codeposition rate and establish the best operating conditions for useful nanocomposites for HARM’s. Recessed electrodes were prepared using X-ray lithography. Partial current density, current efficiency and deposited particle concentration were determined with RDE’s. Cu--Al2O3, Cu-CeO2 and Cu-TiO2 micropost nanocomposites were successfully performed into 500 m deep recesses. Particle concentration and uniformity was dependent upon particle and electrolyte type. The electrodeposition of NiCu composites using nanometric diameter alumina and ceria was examined using the Rotating Cylinder Hull Cell (RCHC). A variation in rotation rate was studied with and without particles. The amount of alumina particles in the alloy composite was much higher than the content of ceria with the same electrolyte loading. Particles altered the deposition rate of Cu and Ni affecting the deposit composition

Yielding of rockfill in relative humidity-controlled triaxial experiments

The final publication is available at Springer via http://dx.doi.org/10.1007/s11440-016-0437-9The paper reports the results of suction controlled triaxial tests performed on compacted samples of two well graded granular materials in the range of coarse sand-medium gravel particle sizes: a quartzitic slate and a hard limestone. The evolution of grain size distributions is discussed. Dilatancy rules were investigated. Dilatancy could be described in terms of stress ratio, plastic work input and average confining stress. The shape of the yield locus in a triaxial plane was established by different experimental techniques. Yielding loci in both types of lithology is well represented by approximate elliptic shapes whose major axis follows approximately the Ko line. Relative humidity was found to affect in a significant way the evolution of grain size distribution, the deviatoric stress-strain response and the dilatancy rules.Peer ReviewedPostprint (author's final draft

FRATERNIDAD PARA LA VIDA DIGNA DE LOS PUEBLOS.(FRATERNITY FOR A WORTHY LIFE OF PEOPLES)

El presente texto pretende relacionar algunas líneas y rutas de análisis como aportes al debate que viene resurgiendo en Latinoamérica en torno al tercer componente no desarrollado de la modernidad: La Fraternidad. Para ello se hará referencia al concepto desde una dimensión política, propia de la modernidad y a la propuesta de la filosofía franciscana.AbstractThis text aims to connect some lines and routes of analysis as contribution to the debate which is reappearing in Latin America around the third non-developed component of modernity: Fraternity. That is why it will be approached from a political dimension, which is proper to modernity and the proposal of Franciscan philosophy

José Martí en Madrid.

Sin resume

Etica y Estética en «El reino interior» de Rubén Darío.

Sin resume

Communication Architecture for Tracking and Interoperable Services at Hospitals: A Real Deployment Experience

Any new hospital communication architecture has to support existing services, but at the same time new added features should not affect normal tasks. This article deals with issues regarding old and new systems’ interoperability, as well as the effect the human factor has in a deployed architecture. It also presents valuable information, which is a product of a real scenario. Tracking services are also tested in order to monitor and administer several medical resources