Examinando por Autor "Multigner, Marta"

Mostrando 1 - 6 de 6

Induction heating in nanoparticles impregnated zeolite
(MDPI, 2020-09-10) Morales, Irene; Muñoz, Marta; Costa, Catia; Alonso, Jose María; Silva, Joao Miguel; Multigner, Marta; Quijorna, Mario; Ribeiro, Maria do Rosário; de la Presa, Patricia
The ultra-stable Y (H-USY) zeolite is used as catalyst for the conversion of plastic feedstocks into high added value products through catalytic cracking technologies. However, the energy requirements associated with these processes are still high. On the other hand, induction heating by magnetic nanoparticles has been exploited for different applications such as cancer treatment by magnetic hyperthermia, improving of water electrolysis and many other heterogeneous catalytic processes. In this work, the heating efficiency of γ-Fe2O3 nanoparticle impregnated zeolites is investigated in order to determine the potential application of this system in catalytic reactions promoted by acid catalyst centers under inductive heating. The γ-Fe2O3 nanoparticle impregnated zeolite has been investigated by X-ray diffraction, electron microscopy, ammonia temperature program desorption (NH3-TPD), H2 absorption, thermogravimetry and dc and ac-magnetometry. It is observed that the diffusion of the magnetic nanoparticles in the pores of the zeolite is possible due to a combined micro and mesoporous structure and, even when fixed in a solid matrix, they are capable of releasing heat as efficiently as in a colloidal suspension. This opens up the possibility of exploring the application at higher temperatures.
Influence of Magnetic Particles and Magnetic Field on Gloss in UV Coating
(MDPI, 2023-09-16) Davoudi, Sorour; Multigner, Marta; Calvez, Ingrid; Hermann, Aurélien; Landry, Véronic
UV-curable coatings possess numerous advantages, including high production rate, low environmental impact, and customizability, making them highly appealing for a wide range of applications. However, one of the greatest challenges in UV-curable coating is achieving an optimal low-gloss surface by adding matting agents to the coating formulation. Therefore, it is essential to find a suitable matting agent type and an efficient roughness creation method to tailor the surface gloss and generate a controlled low-gloss surface. In this study, modified magnetic particles were added to the coating formulation as matting agents, and the UV curing process was conducted under a magnetic field of 10 to 100 mT. The combined effect of adding magnetic particles and magnetic field during UV curing on the coatings’ surface gloss was investigated. The impact of modification, dispersion, and concentration of magnetic particles and the effect of magnetic field force on the final surface gloss and roughness were assessed. Moreover, the effect of the dispersion and concentration of magnetic particles on the photopolymerization of the coating was evaluated. The result indicated that both the magnetic field force and modification of the magnetic particles impact the surface roughness. A CI-APTES 5% wt. sample cured under a 60 mT magnetic field led to the highest decrease in 20° gloss.
Metastable FeMg particles for controlling degradation rate, mechanical properties, and biocompatibility of Poly(l-lactic) acid (PLLA) for orthopedic applications
(Elsevier, 2023) Estrada, Rafael Guillermo; Multigner, Marta; Fagali, Natalia; Lozano, Rosa María; Muñoz, Marta; Cifuentes, Sandra Carolina; Torres, Belén; Lieblich, Marcela
Poly(l-lactic) acid (PLLA) is commonly used in bioabsorbable medical implants, but it suffers from slow degradation rate and rapid decline in mechanical properties for orthopedic applications. To address this drawback, recent research has explored the use of Mg as a filler for PLLA, resulting in composites with improved degradation rate and cytocompatibility compared to neat PLLA. In this study, FeMg powder particles were proposed as fillers for PLLA to investigate the potential of PLLA/FeMg composites for bioabsorbable implants. Cylinder specimens of PLLA, PLLA/Fe, PLLA/ Mg and PLLA/FeMg were prepared using solvent casting followed by thermo-molding. The microstructure, thermal behavior, in vitro degradation behavior in simulated body fluid, mechanical properties and cytocompatibility of these composites were examined. The results indicate that the presence of FeMg particles prevents the deterioration of the composite mechanical properties, at least up to 14 days. Once a certain amount of degradation of the composite is reached, the degradation is faster than that of PLLA. Direct cytotoxicity assays revealed that preosteoblast MC3T3-E1 cells successfully adhered to and proliferated on the PLLA/FeMg surface. The inclusion of a low percentage of Mg into the Fe lattice not only accelerated the degradation rate of Fe but also improved its cytocompatibility. The enhanced degradation rate, mechanical properties, and osteoconductive properties of this composite make it a promising option for temporary orthopedic biomedical devices.
Mg as Bioabsorbable Material
(Elsevier, 2022) Multigner, Marta; Muñoz, Marta; Pulido-González, Nuria; Torres, Belén; Cifuentes, Sandra C.
Magnesium and its alloys are an outstanding option for designing temporary medical devices because of their mechanical properties and biocompatibility. However, to achieve the accurate requirements for different medical treatment, it is necessary to control their degradation process. This can be accomplished by controlling the composition, their microstructure and their surface. This work reviews the role of Mg as bioabsorbable material by remarking different strategies intended to control its degradation process: purification of magnesium, research of alloys firstly developed for industrial applications other than medical, specific design of alloys for biodegradable implants and the incorporation of magnesium as reinforcing phase of biodegradable polymeric matrix composites.
Modulation of Crystallinity through Radiofrequency Electromagnetic Fields in PLLA/Magnetic Nanoparticles Composites: A Proof of Concept
(MDPI, 2021-07-31) Multigner, Marta; Morales, Irene; Muñoz, Marta; Bonache, Victoria; Giacomone, Fernando; de la Presa, Patricia; Benavente, Rosario; Torres, Belén; Mantovani, Diego; Rams, Joaquín
To modulate the properties of degradable implants from outside of the human body represents a major challenge in the field of biomaterials. Polylactic acid is one of the most used polymers in biomedical applications, but it tends to lose its mechanical properties too quickly during degradation. In the present study, a way to reinforce poly-L lactic acid (PLLA) with magnetic nanoparticles (MNPs) that have the capacity to heat under radiofrequency electromagnetic fields (EMF) is proposed. As mechanical and degradation properties are related to the crystallinity of PLLA, the aim of the work was to explore the possibility of modifying the structure of the polymer through the heating of the reinforcing MNPs by EMF within the biological limit range f H < 5 10^9 Am-1s-1. Composites were prepared by dispersing MNPs under sonication in a solution of PLLA. The heat released by the MNPs was monitored by an infrared camera and changes in the polymer were analyzed with differential scanning calorimetry and nanoindentation techniques. The crystallinity, hardness, and elastic modulus of nanocomposites increase with EMF treatment.
Study of the effect of magnetic fields on static degradation of Fe and Fe-12Mn-1.2C in balanced salts modified Hanks’ solution
(Elsevier, 2024-06-29) Limón, Irene; Multigner, Marta; Paternoster, Carlo; Lieblich, Marcela; Torres, Belén; Mantovani, Diego; Rams, Joaquín
Iron and its alloys are attractive as biodegradable materials because of their low toxicity and suitable mechanical properties; however, they generally have a slow degradation rate. Given that corrosion is an electrochemical phenomenon where an exchange of electrons takes place, the application of magnetic fields from outside the body may accelerate the degradation of a ferrous temporary implant. In the present study, we have investigated the effect of alternating and direct low magnetic field (H = 6.5 kA/m) on the corrosion process of pure iron (Fe) and an iron-manganese alloy (FeMnC) in modified Hanks´ solution. A 14-day static immersion test was performed on the materials. The corrosion rate was assessed by mass and cross-sectional loss measurements, scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy before and after degradation. The results show that the presence of magnetic fields significantly accelerates the degradation rate of both materials, with the corrosion rate being twice as high in the case of Fe and almost three times as high for FeMnC. In addition, a homogenous degradation layer is formed over the entire surface and the chemical composition of the degradation products is the same regardless of the presence of a magnetic field.