Utilitzador del simulador Phreeqc per la distribució de contaminants en aigües

En un principi vam començar a fer aquest projecte amb la idea de posar en funcionament el programa Phreeqc i elaborar-ne un manual d’un programa anomenat Phreeqc. El Phreeqc és un programa informàtic que permet realitzar simulacions de la distribució dels contaminants i les diferents espècies químiques en aigües naturals i contaminades a través d’unes paraules clau distribuïdes en quatre barres d’eines (depenent de la seva funció). Aquest programa ja té un manual bastant extens (més de 300 pàgines, annex I); la nostra idea era copsar-ne les idees més importants, i, a partir del manual ja elaborat, els exemples que dóna el programa i observant i utilitzant el programa amb els nostres propis exemples elaborar-ne un de molt més reduït amb els aspectes més bàsics i necessaris per poder dur a terme les simulacions

Tailoring magnetic and mechanical properties of mesoporous single-phase Ni-Pt films by electrodeposition

Homogeneous mesoporous Ni-rich Ni-Pt thin films with adjustable composition have been synthesised by one-step micelle-assisted electrodeposition. The films exhibit a face-centred cubic solid solution (single phase) and their magnetic and mechanical properties can be tuned by varying the alloy composition. In particular, the Curie temperature (TC) is shown to decrease with the Pt content and thin films with a TC close to room temperature (i.e. Ni58Pt42) and below can be produced. Hysteresis loops show a decrease of saturation magnetisation (Ms) and coercivity (Hc) with decreasing Ni content. A comparison of porous and dense films reveals significantly lower saturation magnetic field strength for porous films. Concerning mechanical properties, mainly two trends can be observed: a decrease of the Young's modulus of the nanoporous films with respect to dense films by 10% in average and a progressive increase of Young's modulus with the Ni content from 4.2 GPa to 5.7 GPa in both types of films. The tunability of properties and facility of synthesis make this alloy a promising material for microelectromechanical systems (MEMS)

Electrochemical deposition of NiMnGa alloys

L'article final d'aquest post-print canvia pacialment el títol a: "Single step electrosynthesis of NiMnGa alloys"An electrochemical synthesis route for NiMnGa alloys is presented. Thin films (TFs) of NiMnGa were fabricated by single step electrodeposition from aqueous electrolytes using direct current (DC) over a range of current densities. By meticulous electrolyte tuning, homogeneous TFs with high Ga and Mn content could be achieved at current densities as high as -400 mA cm-2. Detailed compositional analysis of the alloys showed that growth was homogeneous and oxygen content was minimized. TFs plated at very low current densities were found to be nanocrystalline/ amorphous. In order to obtain fully crystalline samples, thermal annealing was carried out. Mechanical characterization was assessed by nanoindentation, and the effect of Ga content on mechanical properties was investigated

Mechanical behaviour of brushite and hydroxyapatite coatings electrodeposited on newly developed FeMnSiPd alloys

Calcium phosphate coatings (CaP) (i.e., brushite and hydroxyapatite) were grown by pulsed current electrodeposition on FeMnSiPd alloys, a newly developed material proposed for biomedical implants. The electrolytic baths contained Ca(NO₃)₂·4H₂O and NH₄H₂PO₄ as precursors. Bath additives, such as H₂O₂ and NaOH, were used to promote hydroxyapatite (HAp) coating formation directly from the bath. The effect of the electrodeposition parameters on the structure, morphology and mechanical performance of the coatings was investigated. Increasing the electrodeposition time from 900s to 3600s resulted in an increase of HAp over the dominant brushite structure. Addition of 2000 ppm of NaOH or 3000 ppm of H₂O₂ also promoted an increase of HAp fraction when compared to the coatings obtained from the additive-free bath. Nonetheless, pure HAp was only achieved with the addition of 4000 ppm of NaOH to the electrolyte. The morphologies of the CaP particles in the coatings ranged from needle- to plate-like structures depending on the electrodeposition parameters and the resulting phases. The mechanical behaviour of the coatings was studied by scratch testing and nanoindentation. As a general trend, the Young's modulus and hardness values of the electrodeposited coatings were lower than those reported for fully-dense HAp, independently of the deposition conditions, because of the porous morphology of the coatings. No signs of cracking or delamination were observed during nanoindentation or scratch tests except for the coating prepared form the electrolyte containing 3000 ppm of H₂O₂

Electrochemical synthesis of bismuth particles : tuning particle shape through substrate type within a narrow potential window

Bismuth (Bi) electrodeposition was studied on Si/Ti/Au, FTO-, and ITO-coated glasses from acidic nitrate solutions with and without gluconate within a narrow potential window (∆E = 80 mV). This potential range was sufficient to observe a change in particle shape, from polyhedrons (including hexagons) to dendrites, the trend being slightly different depending on substrate activity. In all cases, though, the formation of dendrites was favoured as the applied potential was made more negative. Bi particles were more uniformly distributed over the substrate when sodium gluconate was added to the electrolyte. X-ray diffraction analyses of dendrites grown at −0.28 V indicated that they exhibit the rhombohedral phase of Bi and are predominantly oriented along the (003) plane. This orientation is exacerbated at the lowest applied potential (−0.20 V vs. Ag $a gCl) on glass/ITO substrate, for which completed and truncated hexagons are observed from the top view scanning electron microscopy images

Anodic formation of self-organized Ti(Nb,Sn) oxide nanotube arrays with tuneable aspect ratio and size distribution

This is the author's version of a work that was accepted for publication in Electrochemistry communications. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Electrochemistry communications, [33,(2013)] DOI10.1016/j.elecom.2013.04.023).In the present communication one-step anodization is used to prepare large arrays of self-assembled Ti(Nb,Sn) oxide nanotubes on Ti-Nb-Sn alloy. Tuneable nanoscale geometries (unimodal vs. bimodal size distribution with variable length/diameter ratios) can be controllably achieved by varying the anodization conditions, which are highly desirable for enhanced functionalities in widespread applications

Enhanced mechanical properties and microstructural modifications in electrodeposited Fe-W alloys through controlled heat treatments

Among W alloys, Fe-W has seen much attention recently, due to the need of moving toward the design of environmentally friendly materials. Coatings with 4, 16 and 24 at.% of W were electrodeposited from an environmental friendly Fe(III)-based glycolate-citrate bath. The samples were annealed in vacuum at different temperatures up to 800 °C. Different crystalline phases are formed upon annealing: α-Fe, Fe2W, Fe3W3C, Fe6W6C, and FeWO4. Their grain size and distribution within the coating was studied by means of Electron Backscattered Diffraction (EBSD) technique. The effect of annealing on the mechanical properties of the coatings was analyzed performing nanoindentation measurements. The results show a considerable increase of the hardness followed by a rapid decrease at higher temperatures. The highest hardness value, i.e. 16.5 GPa, is measured for the sample with 24 at.% of W after annealing at 600 °C owing to the precipitation of α-Fe crystallites. This study indicates the possibility to substantially increase the hardness of electrodeposited Fe-W coatings by optimization of the annealing treatment. In addition, the critical influence of the carbide and oxide phases on the mechanical properties of alloys is discussed. Hence, Fe-W coatings rich in W can be applied as a possible candidate for protective coating applications at elevated temperatures

Structural and magnetic properties of FexCu1-x sputtered thin films electrochemically treated to create nanoporosity for high-surface-area magnetic components

Sputter deposition is a facile and widely used technique for fabricating thin-film materials. Electrochemical dealloying, on the other hand, is a promising method for creating nanoporosity, and therefore increasing surface area, in metallic materials. Surprisingly, little work has been done on the application of electrochemical dealloying to sputter-deposited thin films. Here, we prepare FexCu1-x thin films by sputter deposition to be then electrochemically treated to create porosity. We investigate the structural and magnetic properties of as-sputtered and electrochemically treated films. We find that the morphology, crystal structure, and magnetic properties are highly dependent on initial film composition. For high copper content films (Fe29Cu71), relative Cu content is found to decrease during the dealloying process. For these films, the crystal structure is not greatly affected by the induced porosity and the porous films show increased saturation magnetization. However, for the more Fe-rich compositions (Fe63Cu37), we find that Fe is preferentially lost and making the films nanoporous induces a crystal structure change from body-centered cubic (bcc) to a mixture of face-centered cubic (fcc) and bccphases. These same porous films show a decrease in saturation magnetization and a large increase in coercivity compared to the as-sputtered films. These films are attractive as high-surface-area magnetic components because of the tunability of their magnetic properties and their high surface area due to porosity. To the best of our knowledge, these results constitute the first example of nanoporous, magnetic thin films by prepared by sputtering and subsequent electrochemical treatment

Síntesi i caracterització de nanopartícules d'òxid de cobalt

L'objectiu d'aquest projecte és sintetitzar i caracteritzar nanopartícules d'òxid de cobalt. Ens interessa estudiar diferents isomorfes de monòxid de cobalt (CoO) ja que són materials nous i se'n desconeixen les propietats; en algunes investigacions s'intueix un comportament antiferromagnètic la qual cosa les fa especialment interessants per aplicacions magnètiques

Electroless Palladium-Coated Polymer Scaffolds for Electrical Stimulation of Osteoblast-Like Saos-2 Cells

Three-dimensional porous scaffolds offer some advantages over conventional treatments for bone tissue engineering. Amongst all non-bioresorbable scaffolds, biocompatible metallic scaffolds are preferred over ceramic and polymeric scaffolds, as they can be used as electrodes with different electric field intensities (or voltages) for electric stimulation (ES). In the present work we have used a palladium-coated polymeric scaffold, generated by electroless deposition, as a bipolar electrode to electrically stimulate human osteoblast-like Saos-2 cells. Cells grown on palladium-coated polyurethane foams under ES presented higher proliferation than cells grown on foams without ES for up to 14 days. In addition, cells grown in both conditions were well adhered, with a flat appearance and a typical actin cytoskeleton distribution. However, after 28 days in culture, cells without ES were filling the entire structure, while cells under ES appeared rounded and not well adhered, a sign of cell death onset. Regarding osteoblast differentiation, ES seems to enhance the expression of early expressed genes. The results suggest that palladium-coated polyurethane foams may be good candidates for osteoblast scaffolds and demonstrate that ES enhances osteoblast proliferation up to 14 days and upregulate expression genes related to extracellular matrix formation