A microscopic level insight into Pt doped TiZn (001) surface for hydrogen energy storage usage

The interaction of hydrogen and platinum with B2-TiZn (001) surface was studied by means of spin-polarized density functional theory (DFT) calculations. H and Pt on TiZn adsorption energies were calculated taking into account high symmetry adsorption sites. Both the adatoms prefer to be adsorbed on the hollow site where the higher coordination number allows them to minimize the repulsion among the overlapping charge densities of them and the surface. Furthermore, the influence of pre-adsorbed Pt on the H adsorption was analyzed in detail. It was found that this process is enhanced in Pt doped TiZn surface. The electronic structures and changes in the chemical bonding for both the adsorbates on the Ti alloy surface were computed by density of states (DOS) and overlap population (OP) methods, concluding that 3dx2-y2, 3dz2 and 3pz Ti, 5pz Pt orbitals play an important role in H adsorption, as well as it was deduced that the strong overlap between Pt and Ti orbitals allows H atoms to bond more effectively on the surface. Bader's analysis revealed that H and Pt act as electron acceptors, whereas surface Ti-atoms act as electron donors during the H adsorption process.Fil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Juan, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Marchetti, Jorge Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Norwegian University of Life Sciences; NoruegaFil: German, Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin

A DFT study of H2 adsorption on Pdn/SnO2 (110) surfaces (n = 1−10)

Hydrogen adsorption on palladium atoms pre-adsorbed on a tin oxide semiconductor has been studied and compared with H2 adsorption on a bare SnO2. By means of density functional theory calculations, the preferential number of Pd atoms and their geometry as well as the physisorption and chemisorption of H2 is analyzed on these surfaces. Namely, bare stoichiometric SnO2 (110) and Pd-doped SnO2 (110) surface systems are considered. It is found that Pd atoms tend to form clusters composed of 5 atoms. When considering sites with a favorable adsorption energy ( >0.10 eV), these pre-adsorbed Pd5 clusters increase the number of active sites for H2 chemisorption from 5 – in the case of the bare surface – to 16 for the same surface area. Bare SnO2 (110) surfaces also present 5 potential sites for physisorption while Pd5/SnO2 surface presents 10 potential physisorption sites when applying the same adsorption energy criterion. Although dissociative H2 adsorption is energetically more favorable for bare SnO2 than for Pd5/SnO2, the molecular H2 adsorption is slightly more favorable for the doped system.Fil: German, Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad de Valladolid; EspañaFil: Pistonesi, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Química; Argentin

Ruthenium decorated single walled carbon nanotube for molecular hydrogen storage: A first-principle study

Molecular hydrogen storage on Ruthenium (Ru) decorated single-walled carbon nanotube (SWCNT) has been studied by using spin-polarized density functional theory (DFT). When a Ru atom is adsorbed on SWCNT, the Bader analysis reveals that Ru transfers a charge of 0.44e to SWCNT. Accordingly, Ru acts as adsorption center for H2 molecules; thus, it can hold up to four H2 molecules with an adsorption energy (Eads) of 0.93 eV/H2. A uniform addition of Ru atoms on SWCNT shows that this nanomaterial can adsorb up to five Ru without clustering. Each Ru atom of 5Ru-decorated SWCNT system can bind up to four H2 molecules involving an Eads of 0.83 eV/H2. After H2 molecules adsorption, Ru atoms shifted from a near hollow site to a bridge site. Moreover, Ru-decorated systems reduce their magnetic moment when the number of H2 molecules increase from 2 mB to 0 mB.Fil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Juan, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: German, Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad de Valladolid; Españ

Assessing structure and dynamics of fibrinogen films on silicon nanofibers: Towards hemocompatibility devices

An enhanced knowledge of the interaction of proteins with the surfaces of implantable materials, particularly regarding fibrinogen (Fb), is fundamental for understanding cellular events and the overall host response. Thinking of future use of Si-nanofibers as three-dimensional (3D) scaffolds for construction of implantable artificial devices, the correlation among the material surface characteristics and the amount, structure and distribution of adsorbed Fb molecules are analyzed. The Fb adsorption process occurs in a stepwise fashion with an initial rapid adsorption, an intermediate reorganization and finally a second slower adsorption regime over a longer period of time. There is a partial desorption of the protein after the first adsorption process, which demonstrates that this step is reversible until 2 × 104 s. Nevertheless the whole process is irreversible, with a high distortion of the original material morphology. The limiting value for the adsorbed Fb surface concentration is about 270 ± 20 μg dm-2; more than three times the adsorption capacity of non fibrillar, 2D or 3D, scaffolds. The fibrous structure and the similitude in size between the substrate (d = 30-50 nm) and the Fb molecules (47-50 nm) are proposed to be the key to the enhanced adsorption process and the acquired final topography of the material.Fil: Hassan, Natalia. Universidad de Santiago de Compostela. Facultad de Física; EspañaFil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ruso, Juan M.. Universidad de Santiago de Compostela. Facultad de Física; EspañaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Mimicking natural fibrous structures of opals by means of a microemulsion-mediated hydrothermal method

Silica-based nanomaterials are of great interest because of their potential applications in constructing electronic and optoelectronic nanodevices. Especially significant are those that combine the properties of photonic crystal with a fibrous semiconductor structure. Here we report the use of microemulsion droplet systems as a simple and controllable route for the synthesis of 3D opals materials with an unusual fibrous microstructure similar to those that exist in nature. By this method, we demonstrate the creation of very long fibrils of 30-50 nm diameter and more than 20 μm length showing simultaneous short and long wavelength light emissions and band gap values (5.50 and 4.41 eV) comparable to those obtained for silicon-based metal oxide semiconductors. © 2011 American Chemical Society.Fil: Hassan, Natalia. Universidad de Santiago de Compostela; EspañaFil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ruso, Juan M.. Universidad de Santiago de Compostela; EspañaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Tecnología Co-Construida :En base a madera de Alamo

El sistema constructivo "Paranacito" es el resultado de una tecnología que fue desarrollada y diseñada de manera colectiva entre diversos actores en la localidad de Villa Paranacito (EntreRíos). Este sistema se inscribe en el marco de varios proyectos de investigación cuyos objetivos giraban en torno al diseño e implementación de un circuito productivo interactoral de casa-partes de madera para contribuir al fortalecimiento del perfil productivo del lugar. En ese sentido, se diseñó y desarrollo una tecnología para vivienda íntegramente con madera de álamo, materia prima obtenida de la producción forestal de la localidad y la región en el interior de las islas del delta entrerriano. El sistema constructivo Paranacito, ajustó su desarrollo tecnológico en función de secciones y longitudes utilizadas preferentemente en la localidad para otros destinos en virtud de no generar cortes especiales improductivos. Dicho sistema prefabricado se conforma a partir de varios componentes tales como envolvente lateral (paneles bajos y altos), envolventesuperior (paneles de techo y cabriadas) y aberturas.Fil: Peyloubet, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad. Universidad Nacional de Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad; ArgentinaFil: Fenoglio, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad. Universidad Nacional de Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad; ArgentinaFil: Verdinelli, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro Experimental de la Vivienda Económica; ArgentinaFil: Barea, German Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro Experimental de la Vivienda Económica; Argentin

Hydrophile-lipophile balance (HLB) of n-alkane phosphonic acids and theirs salts

As a previous step in their application as emulsifiers, here we performed a study of the hydrophile-lipophile balance (HLB) properties of decyl (C10H21PO3H2), dodecyl (C12H25PO3H2), tridecyl (C13H27PO3H2) phosphonic acids and their mono and disodic salts. Two different methods (Griffin and Greenwald et al. methods) were applied. The HLB values along with the -PO3H2; -PO3HNa and PO3Na2 HLB group numbers found by Greenwald et al. method were comparable to those obtained for similar structure surfactants. The HLB computed by Griffin emulsion technique strongly depends on the nature of the emulsifier mixture compounds, and was shown inappropriate to study this kind of surfactants. This fact is interpreted because of the hydrocarbon/water structure. © 2007 Elsevier B.V. All rights reserved.Fil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Schulz, Pablo Carlos. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Vuano, Bruno Mario. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin

Role of interfacial elasticity of microemulsions on the morphology of TiO2 nanostructures: stiff templates versus flexible templates

The effects of temperature and interfacial elasticity on nanostructured titanium dioxide (TiO2) microemulsions templated materials have been investigated. The aim was to establish a simple and rapid selection of the best experimental conditions for achieving some required material property. TiO2 materials have been prepared through reactive microemulsion precipitation. The effect of microemulsion process parameters (temperature and oil phase density) on the final material characteristics has been investigated. The titania nanopowders were characterized by Xray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and N2 adsorption– desorption isotherms. The results obtained by different process conditions show that the nonpolar phase density and temperature of microemulsions have a great influence on the final characteristics of the obtained material. A reduction of the microemulsion oil density causes a significant decrease in the particle agglomeration and an augment of the material-specific surface area and pore volume. At the same time, rutile is favored over anatase phase. The increase of template microemulsion temperature produces, in some systems, a morphology change from granular to a bicontinuous structure.Fil: Messina, Paula Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Química del Sur; Argentina.;Fil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Química del Sur; Argentina.;Fil: Pieroni, Olga Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Química del Sur; Argentina.;Fil: Ruso, Juan Manuel. Universidad de Santiago de Compostela. Facultad de Física. Grupo de Materia Blanda y Biofísica Molecular; España

Regarding the effect that different twin-tailed surfactant have on a solid stabilized petroleum emulsion

An industrial petroleum emulsion stabilized by colloidal silica particles was treated with four different twin-tailed surfactants: sodium bis-2-(ethylhexyl) sulfosuccinate (AOT), didodecylammonium bromide (DDAB), calcium oleate (Ca(OL)2), and dioctadecyldimethylammonium bromide (DODAB). Fourier transform infrared (FT-IR) spectroscopy, optical microscopy, centrifuge test, and conductivity measurement were employed to determine the effect of the amphiphile molecules on the crude oil emulsion. AOT and DDAB produce emulsion breakdown, while Ca(OL)2 does not alter the emulsion stability and DODAB produces an extra stabilization of it. The AOT adsorption at the oil–water droplet interface is a spontaneous process, which promoted the emulsion breakdown through an interdroplet interaction mechanism. DDAB needs extra energy (via centrifugation) to destabilize the emulsion. Ca(OL)2 dissolves in oil phase and remains there without altering the emulsion strength, while DODAB increases the emulsion stability.Fil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Pieroni, Olga Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Schulz, Pablo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Inversion Properties of n-Alkane Phosphonic Acids Stabilized Emulsions: HLB Dependence

The emulsifier properties of n-alkane phosphonic acids (C10H21PO3H2; C12H25PO3H2 and C13H27PO3H2) and their mono- and di-sodic salts were studied, with emphasis on the morphological and dynamical inversion properties as a function of their neutralization degree. Maximum stabilization properties were appreciated for C10PO3H2 and C12PO3H2 while not for C13PO3H2. Such fact is associated to their odd number of carbon atoms chain, which is the origin of the intrachain constraints on the tail-chain flexibility. © Taylor & Francis Group, LLC.Fil: Verdinelli, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Vuano, Bruno Mario. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; ArgentinaFil: Schulz, Pablo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin