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Artículos SCI



2020


Tailoring CrNx stoichiometry and functionality by means of reactive HiPIMS


Sanchez-Lopez, JC; Caro, A; Alcala, G; Rojas, TC
Surface & Coatings Technology, 401 (2020) 126235
Tribología y Protección de Superficies

ABSTRACT

This work presents a complete study of the influence of HiPIMS pulse characteristics on the microstructure, chemical composition, mechanical and oxidation resistance properties of CrN thin films. The investigated parameters were frequency and pulse length at two different nitrogen fluxes, maintaining constant the duty cycle conditions (2%). The effect of a negative bias of 100 V was investigated in a particular case. By changing the synthesis conditions, it was possible to tailor the N/Cr ratio and thus to control the CrNx stoichiometry from x = 0.63 to 1.10. The selection of longer pulses (shorter frequencies) generates more disordered structures with lower N/Cr ratios. This is reflected in higher hardness and elastic modulus values on despite of a lower oxidation resistance due to existence of larger concentration of N vacancies. The best oxidation resistance is obtained at the highest peak current combined with additional ion bombardment provided by substrate biasing. The present results open the possibilities of modifying chemical composition and engineering surfaces by changing exclusively the pulse conditions in HiPIMS deposition processes.


Noviembre, 2020 | DOI: 10.1016/j.ceramint.2020.09.024

Graphene-coated Ti-Nb-Ta-Mn foams: A promising approach towards a suitable biomaterial for bone replacement


Lascano, S; Chavez-Vasconez, R; Munoz-Rojas, D; Aristizabal, J; Arce, B; Parra, C; Acevedo, C; Orellana, N; Reyes-Valenzuela, M; Gotor, FJ; Arevalo, C; Torres, Y
Surface & Coatings Technology, 401 (2020) 126250
Reactividad de Sólidos

ABSTRACT

The design of bone implants with proper biological and mechanical properties remains a challenge in medical implantology. The use of bioactive coatings has been shown to improve the biocompatibility of the implant surface. In this study, a new approach including porous scaffolds, beta-Ti alloys and nanocoatings to design new bone implants is presented. Porous Ti-Nb-Ta-xMn alloys (x: 2, 4, and 6 wt%) substrates were obtained by powder metallurgy and the effect of the porosity and Mn content on mechanical properties was studied. CVD single-layer graphene was transferred onto the porous substrates that presented the best mechanical response (x: 4 wt%) for further evaluation of in vitro cell behavior (biocompatibility and cell adhesion). Cytotoxicity and biocompatibility tests confirmed that cell adhesion and proliferation were successfully achieved on graphene-coated porous substrates, confirming these systems are potential candidates for using in partial bone tissue replacement.


Noviembre, 2020 | DOI: 10.1016/j.surfcoat.2020.126250

Enhanced Directional Light Extraction from Patterned Rare-Earth Phosphor Films


Cabello-Olmo, E; Molet, P; Mihi, A; Lozano, G; Miguez, H
Advanced Optical Materials, (2020)2001611
Materiales Ópticos Multifuncionales

ABSTRACT

The combination of light‐emitting diodes (LEDs) and rare earth (RE) phosphors as color‐converting layers comprises the basis of solid‐state lighting. Indeed, most LED lamps include a photoluminescent coating made of phosphor material, i.e., crystalline matrix suitably doped with RE elements, to produce white light from a blue or ultraviolet LED chip. Transparent phosphor‐based films constitute starting materials for new refined emitters that allow different photonic designs to be implemented. Among the different photonic strategies typically employed to tune or enhance emission, surface texturing has proved its versatility and feasibility in a wide range of materials and devices. However, most of the nanofabrication techniques cannot be applied to RE phosphors directly because of their chemical stability or because of their cost. The first monolithic patterned structure of down‐shifting nanophosphors with square arrays of nanoholes with different lattice parameters is reported in this study. It is shown that a low‐cost soft‐nanolithography procedure can be applied to red‐emitting nanophosphors (GdVO4:Eu3+ nanocrystals) to tune their emission properties, attaining a twofold directional enhancement of the emitted light at predesigned emission wavelengths in specific directions.


Noviembre, 2020 | DOI: 10.1002/adom.202001611

Electrical and reaction performances of packed-bed plasma reactors moderated with ferroelectric or dielectric materials


Gomez-Ramirez, A; Alvarez, R; Navascues, P; Garcia-Garcia, FJ; Palmero, A; Cotrino, J; Gonzalez-Elipe, AR
Plasma Processes and Polymers, (2020) e2000193
Nanotecnología en Superficies y Plasma

ABSTRACT

The operational behavior of packed-bed plasma reactors depends on the dimension, shape, and chemical properties of the pellets used as moderators, but little information exists about the influence of their specific dielectric properties. Herein, we comparatively study the electrical behavior of a packed-bed reactor filled with pellets of either dielectric (Al2O3 and glass) or ferroelectric (BaTiO3 and lead zirconate titanate) materials. We found that plasma current was higher for ferroelectrics and presented a nonlineal dependence on voltage. Moreover, for BaTiO3, we found a drastic decrease at around its relatively low Curie temperature. Differences in electrical behavior have a direct effect on the reactor performance, as illustrated for the ammonia synthesis, demonstrating the importance of moderator material dielectric properties and their dependence on temperature.


Noviembre, 2020 | DOI: 10.1002/ppap.202000193

Unraveling Discharge and Surface Mechanisms in Plasma-Assisted Ammonia Reactions


Navascues, P; Obrero-Perez, JM; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
ACS Sistainable Chemistry & Engineering, 8 (2020) 14855-14866
Nanotecnología en Superficies y Plasma

ABSTRACT

Current studies on ammonia synthesis by means of atmospheric pressure plasmas respond to the urgent need of developing less environmentally aggressive processes than the conventional Haber-Bosch catalytic reaction. Herein, we systematically study the plasma synthesis of ammonia and the much less investigated reverse reaction (decomposition of ammonia into nitrogen and hydrogen). Besides analyzing the efficiency of both processes in a packed-bed plasma reactor, we apply an isotope-exchange approach (using D-2 instead of H-2) to study the reaction mechanisms. Isotope labeling has been rarely applied to investigate atmospheric plasma reactions, and we demonstrate that this methodology may provide unique information about intermediate reactions that, consuming energy and diminishing the process efficiency, do not effectively contribute to the overall synthesis/decomposition of ammonia. In addition, the same methodology has demonstrated the active participation of the interelectrode material surface in the plasma-activated synthesis/decomposition of ammonia. These results about the involvement of surface reactions in packed-bed plasma processes, complemented with data obtained by optical emission spectroscopy analysis of the plasma phase, have evidenced the occurrence of inefficient intermediate reaction mechanisms that limit the efficiency and shown that the rate-limiting step for the ammonia synthesis and decomposition reactions are the formation of NH* species in the plasma phase and the electron impact dissociation of the molecule, respectively.


Octubre, 2020 | DOI: 10.1021/acssuschemeng.0c04461

Multiple pollutants removal by functionalized heterostructures based on Na-2-Mica


Pazos, MC; Bravo, LR; Ramos, SE; Osuna, FJ; Pavon, E; Alba, MD
Applied Clay Science, 196 (2020) 105749
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT

Organomica, C8-2-Mica, was obtained from a high charged synthetic mica, Na-2-Mica, by cation exchange reaction with octylammonium cations and these were used to host other bulky guest species such as polyhydroxy aluminium cations, Al(13)20. The hydrolization of 3-mercaptopropyltrimethoxysilane (MPTMS) allowed the covalent attachment with hydroxyl groups of the oligomeric cation, providing thiol groups that create specific adsorption sites, Al(13)20/SH. The structure of the adsorbents was analysed by XRD and Infrared spectroscopy and these were tested as an adsorbent for the removal of zinc and herbicide MCPA from aqueous solutions. C8-2-Mica was the best adsorbent for MCPA and thiol groups favoured the adsorption of Zn2+. Moreover, Al(13)20/SH showed excellent adsorptive properties for the simultaneous adsorption of MCPA and Zn2+.


Octubre, 2020 | DOI: 10.1016/j.clay.2020.105749

Internal quantum efficiency and time signals from intensity-modulated photocurrent spectra of perovskite solar cells


Riquelme, A; Galvez, FE; Contreras-Bernal, L; Miguez, H; Anta, JA
Journal of Applied Physics, 128 (2020) 133103
Materiales Ópticos Multifuncionales

ABSTRACT

Intensity Modulated Photocurrent Spectroscopy (IMPS) is a small-perturbation optoelectronic technique that measures the quantum efficiency of a photoelectrochemical device as a function of optical excitation frequency. Metal Halide Perovskites (MHPs) are mixed electronic-ionic semiconductors with an extraordinary complex optoelectronic behavior and a record efficiency surpassing 25%. In this paper, we propose a simplified procedure to analyze IMPS data in MHPs based on the analysis of the internal quantum efficiency and the time signals featuring in the frequency spectra. In this procedure, we look at the change of each signal when optical excitation wavelength, photon flux, and temperature are varied for an archetypical methyl ammonium lead iodide solar cell. We use drift-diffusion modeling and comparison with relatively simpler dye-sensitized solar cells (DSC) with viscous and non-viscous electrolytes to help us to understand the origin of the three signals appearing in MHP cells and the measurement of the internal quantum efficiency.


Octubre, 2020 | DOI: 10.1063/5.0013317

Upgrading the PtCu intermetallic compounds: The role of Pt and Cu in the alloy


Castillo, R; Garcia, ED; Santos, JL; Centeno, MA; Sarria, FR; Daturi, M; Odriozola, JA
Catalysis Today, 356 (2020) 390-398
Química de Superficies y Catálisis

ABSTRACT

This work is devoted to the study of the role of both metals in the intermetallic PtxCuy/ γ Al2O3 catalysts commonly employed in CO-PROX reaction. Therefore, monometallic Pt and Cu based catalysts and PtCu intermetallic compound with different molar ratios (Pt3Cu1 and Pt1Cu3) supported catalysts were carefully synthesized and deeply characterized. Room temperature CO adsorptions by FTIR spectroscopy were carried out on the mono- and intermetallic catalysts being the monometallic catalyst determinant for the study. From the analysis of the nature of the platinum surface in Pt/ γ Al2O3, we have demonstrated that the role of Pt sites is based in the CO dissociation for the CO2 formation and also how the platinum surface is partially blocked by leftovers from the synthesis. Moreover, the study of the Cu/ γ Al2O3 and the bimetallic catalysts PtxCuy/ γ Al2O3 allowed elucidating the effect of the copper in the metallic site and support interphase as well as the role of copper in the hydrocarbon oxidation.


Octubre, 2020 | DOI: 10.1016/j.cattod.2019.11.026

Tribological performance of Nb-C thin films prepared by DC and HiPIMS


Sala, N; Abad, MD; Sanchez-Lopez, JC; Cruz, M; Caro, J; Colominas, C
Materials Letters, 277 (2020) 12834
Tribología y Protección de Superficies

ABSTRACT

Nanostructured NbC thin films with variable contents of Nb and C were prepared by direct current (DC) magnetron sputtering, and for the first time, via high power impulse magnetron sputtering (HiPIMS) searching for an improvement in the tribological properties. X-ray diffraction shows that increasing the carbon incorporation, the crystalline composition evolves from Nb2C to NbC phase. Further carbon enrichment leads to a nanocomposite structure formed by small NbC crystals (8-14 nm) dispersed in a-C matrix. The friction coefficient varied from high friction (0.8) to low friction (0.25) and the hardness values between 20 and 11 GPa depending on the film composition. A densification of the coatings by changing the methodology from DC to HiPIMS was not observed. 


Octubre, 2020 | DOI: 10.1016/j.matlet.2020.128334

Microstructure and thermal conductivity of Si-Al-C-O fiber bonded ceramics joined to refractory metals


Vera, MC; Martinez-Fernandez, J; Singh, M; Casalegno, V; Balagna, C; Ramirez-Rico, J
Materials Letters, 276 (2020) 128203
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT

We explore joining Si-Al-C-O fiber-bonded ceramics to Cu-clad-Mo using an Ag-Ti-Cu brazing alloy. A temperature of 900 degrees C and times in the range of 10-20 min are required to obtain sound joints irrespectively of the fiber orientation. The reaction layer is 1-2 mu m thick and free of pores and defects. The thermal conductivity of the joined samples is well described considering that the metal and the ceramic are in series for thermal resistance. This implies that the joint is highly conductive and forms an almost perfect 


Octubre, 2020 | DOI: 10.1016/j.matlet.2020.128203

Tailoring materials by high-energy ball milling: TiO2 mixtures for catalyst support application


Rinaudo, MG; Beltran, AM; Fernandez, MA; Cadus, LE; Morales, MR
Materials Today Chemistry, 17 (2020) 100340
Materiales Nanoestructurados y Microestructura

ABSTRACT

We carried out a rational design of catalyst supports by high-energy ball milling. Tailored mixtures of TiO2 crystalline phases were obtained using rotational speed and milling time as variable parameters. Polymorphic transformation from anatase to rutile through high-pressure TiO2 (II) as intermediate was confirmed by X-ray Diffraction (XRD), Raman Spectroscopy and Transmission Electron Microscopy (TEM). Also, starting material doubled its specific surface area due to particle fragmentation, as confirmed by surface area of Brunauer-Emmet-Teller (S-BET) and Scanning Electron Microscopy (SEM). Defects introduced during milling process generated oxygen vacancies in the surface and bulk of supports, as evidenced by X-ray Photoelectron Spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR). Furthermore, longer milling time increased reducibility and oxygen mobility of supports, as observed by H-2 Temperature Programmed Reduction (H-2-TPR) and O-2 Temperature Programmed Desorption (O-2-TPD). Phase composition remained unchanged even under extreme conditions, highlighting the stability of unusual TiO2 (II) phase. Properties achieved in present materials could benefit metal-support interactions and play a major role in supported catalysts. 


Septiembre, 2020 | DOI: 10.1016/j.mtchem.2020.100340

Elucidating esterification reaction during deposition of cutin monomers from classical molecular dynamics simulations


Bueno, OVM; Benitez, JJ; San-Miguel, MA
Journal of Molecular Modeling, 26 (2020) 280
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT

The structural behavior of some cutin monomers, when deposited on mica support, was extensively investigated by our research group. However, other events, such as esterification reaction (ER), are still a way to explore. In this paper, we explore possible ER that could occur when these monomers adsorb on support. Although classical molecular dynamics simulations are not able to capture reactive effects, here, we show that they become valuable strategies to analyze the initial structural configurations to predict the most favorable reaction routes. Thus, when depositing aleuritic acid (ALE), it is observed that the loss of capacity to form self-assembled (SA) systems favors different routes to occur ER. In pure ALE bilayers systems, an ER is given exclusively through the -COOH and primary -OH groups. In pure ALE monolayers systems, the ER does not happen when the system is self-assembled. However, for disorganized systems, it is able to occur by two possible routes: -COOH and primary -OH (route 1) and -COOH and secondary -OH (route 2). When palmitic acid (PAL) is added in small quantities, ALE SAMs can now form an ER. In this case, ER occurs mostly through the -COOH and secondary -OH groups. However, when the presence of PAL is dominant, ER can occur with either of both possibilities, that is, routes 1 and 2.


Septiembre, 2020 | DOI: 10.1007/s00894-020-04544-9

Bimetallic PdAu catalysts for formic acid dehydrogenation


Santos, JL; Leon, C; Monnier, G; Ivanova, S; Centeno, MA; Odriozola, JA
International Journal of Hydrogen Energy, 45 (2020) 23056-23068
Química de Superficies y Catálisis

ABSTRACT

A series of monometallic and bimetallic palladium gold catalyst were prepared and studied for the formic acid dehydrogenation reaction. Different Pd/Au compositions were employed (PdxAu100-x, where x = 25; 50 and 75) and their impact on alloy structure, particle size and dispersion was evaluated. Active phase composition and reaction parameters such as temperature, formic acid concentration or formate/formic acid ratio were adjusted to obtain active and selective catalyst for hydrogen production. An important particle size effect was observed and related to Pd/Au composition for all bimetallic catalysts. 


Septiembre, 2020 | DOI: 10.1016/j.ijhydene.2020.06.076

Free-Carbon Surface for PtCu Nanoparticles: An In Situ Near Ambient Pressure X-ray Photoelectron Spectroscopy Study


Castillo, R; Navarro-Jaen, S; Romero-Sarria, F; Perez-Dieste, V; Escudero, C; Centeno, MA; Daturi, M; Odriozola, JA
Journal of Physical Chemistry C, 124 (2020) 19046-19056
Química de Superficies y Catálisis

ABSTRACT

Usually, nanoparticle synthesis methodologies require the use of organic molecules (capping agent, solvent molecules, etc.), which results in carbon deposits on the nanoparticle surface. These residues modify the surface properties mainly affecting the catalytic behavior. In this work, unsupported poly(vinylpyrrolidone) (PVP)-stabilized PtCu (1:3 molar ratio) bimetallic alloy nanoparticles were synthetized and characterized. An alternative surface cleaning method has been designed, which successfully removes the presence of organic fragments. To address this key issue, we have combined a first nanoparticle washing step with a near ambient pressure X-ray photoelectron spectroscopy (NAPXPS) study in order to obtain a clean active site and the total understanding of the carbon elimination mechanism. The dynamic evolution of the surface organic species composition under different gas mixtures at 750 mTorr and 350 degrees C has been studied, and only under CO2 exposure, NAPXPS analysis revealed a total availability of the active site by the removal of the organic nanoparticle coating.


Septiembre, 2020 | DOI: 10.1021/acs.jpcc.0c04713

The wrinkling concept applied to plasma-deposited polymer-like thin films: A promising method for the fabrication of flexible electrodes


Thiry, Damien; Vinx, Nathan; Damman, Pascal; Aparicio, Francisco J.; Tessier, Pierre-Yves; Moerman, David; Leclere, Philippe; Godfroid, Thomas; Deprez, Sylvain; Snyders, Rony
Plasma Processes and Polymers, 17 (2020) e2000119
Nanotecnología en Superficies y Plasma

ABSTRACT

In this communication, we report on an innovative solvent-free method that allows for the design of nano-/micropatterns with tuneable dimensions. Our approach is based on the spontaneous wrinkling phenomenon taking place in a bilayer system formed by a mechanically responsive bottom plasma polymer layer and a top aluminum thin film. The dimensions of the wrinkles can be adjusted in a wide range (i.e., from nanometer to micrometer range) by modulating the cross-linking density as well as the thickness of the plasma polymer layer. Finally, it is demonstrated that these wrinkled surfaces could efficiently be used as flexible electrodes. The whole set of our data unambiguously reveals the attractiveness of our method for the fabrication of the micro-/nanopattern with dimensions on demand.


Septiembre, 2020 | DOI: 10.1002/ppap.202000119

Synthesis of all equiatomic five-transition metals High Entropy Carbides of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups by a low temperature route


Chicardi, E; Garcia-Garrido, C; Hernandez-Saz, J; Gotor, FJ
Ceramics International, 46 (2020) 21421-21430
Reactividad de Sólidos

ABSTRACT

The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC5, TiZrHfVTaC5, TiZrHfNbTaC5, TiZrVNbTaC5, TiHfVNbTaC5 and ZrHfVNbTaC5, were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC5, TiZrVNbTaC5 and ZrHfVNbTaC5, were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800-2200 degrees C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites.


Septiembre, 2020 | DOI: 10.1016/j.ceramint.2020.05.240

Novel procedure for laboratory scale production of composite functional filaments for additive manufacturing


Diaz-Garcia, A; Law, JY; Cota, A; Bellido-Correa, A; Ramirez-Rico, J; Schafer, R; Franco, V
Materials Today Communications, 24 (2020) 101049
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT

Successful 3D printing by material extrusion of functional parts for new devices requires high quality filaments. Uniform homogeneity and good dispersion of particles embedded in filaments typically takes several cycles of extrusion or well-prepared feedstock by injection molding, industrial kneaders or twin-screw compounding. These methods need specific production devices that are not available in many laboratories non-specialized in polymer research, such as those working on different material science and technology topics that try to connect with additive manufacturing. Therefore, laboratory studies are usually limited to compositions and filler concentrations provided by commercial companies. Here, we present an original laboratory scale methodology to custom-prepare the feedstock for extruding magnetic composite filaments for fused filament fabrication (FFF), which is attainable by a desktop single-screw extruder. It consists in encapsulating the fillers in custom made capsules that are used as feedstock and reach the melting area of the extruder maintaining the same concentration of fillers. Results have shown that our approach can create smooth and continuous composite filaments with good homogeneity and printability with fine level of dimensional control. We further show the good dispersion of the particles in the composite filament using X-Ray Tomography, which enabled a 3D reconstruction of the spacial distribution of the embedded magnetic particles. The major advantage of this new way of preparing the composite feedstock is that it avoids the hassle of multiple extrusion runs and industrial machinery, yet providing uniform filaments of well controlled filler concentration, which is predictable and reproducible. The proposed methodology is suitable for different polymer matrices and applicable to other functional particle types, not just limited to magnetic ones. This opens an avenue for further laboratory scale development of novel functional composite filaments, useful for any community. This democratization of complex filament preparation, including consumers preparing their own desired uniform novel filaments, will facilitate to unify efforts nearing 3D printing of new functional devices.


Septiembre, 2020 | DOI: 10.1016/j.mtcomm.2020.101049

Experimental evidence of HCO species as intermediate in the fischer tropsch reaction using operando techniques


Diaz-Sanchez, RM; de-Paz-Carrion, A; Serrera-Figallo, MA; Torres-Lagares, D; Barranco, A; Leon-Ramos, JR; Gutierrez-Perez, JL
Applied Catalysis B-Environmental, 272 (2020) 119032
Química de Superficies y Catálisis

ABSTRACT

Fischer Tropsch's reaction, known from 1925, receives special attention nowadays due to its key role in the CO2 or biomass valorization to liquid fuels and chemicals. Several aspects on the exact mechanism or the role of water in this reaction are not yet completely clear. Formyl species, HCO, have been proposed as the most probable reaction intermediate, but they have never been observed under operation conditions closed to the real ones. In this work, using DRIFTS-MS operando techniques, HCO intermediates are detected under a H2/CO flow and 200 °C. IR bands at 2900 cm−1 and 1440 cm−1 attributed to ν(C–H) and δ(HCO) vibrations modes characterize these species. Evolution of these bands with the reaction time evidences its high reactivity with OH groups, which explains the positive effect of water on the CO conversion previously observed.


Septiembre, 2020 | DOI: 10.1016/j.apcatb.2020.119032

Design of a nanoprobe for high field magnetic resonance imaging, dual energy X-ray computed tomography and luminescent imaging


Gonzalez-Mancebo, D; Becerro, AI; Corral, A; Garcia-Embid, S; Balcerzyk, M; Garcia-Martin, ML; de la Fuente, JM; Ocana, M
Journal of Colloid and Interface Science, 573 (2020) 278-286
Materiales Coloidales

ABSTRACT

The combination of different bioimaging techniques, mainly in the field of oncology, allows circumventing the defects associated with the individual imaging modalities, thus providing a more reliable diagnosis. The development of multimodal endogenous probes that are simultaneously suitable for various imaging modalities, such as magnetic resonance imaging (MRI), X-ray computed tomography (CT) and luminescent imaging (LI) is, therefore, highly recommended. Such probes should operate in the conditions imposed by the newest imaging equipment, such as MRI operating at high magnetic fields and dual-energy CT. They should show, as well, high photoluminescence emission intensity for their use in optical imaging and present good biocompatibility. In this context, we have designed a single nanoprobe, based on a core-shell architecture, composed of a luminescent Eu3+:Ba0.3Lu0.7F2.7 core surrounded by an external HoF3 shell that confers the probe with very high magnetic transverse relaxivity at high field. An intermediate, optically inert Ba0.3Lu0.7F2.7 layer was interposed between the core and the shell to hinder Eu3+-Ho3+ cross-relaxation and avoid luminescence quenching. The presence of Ba and Lu, with different K-edges, allows for good X-ray attenuation at high and low voltages. The core-shell nanoparticles synthesized are good potential candidates as trimodal bioprobes for MRI at high field, dual-energy CT and luminescent imaging. 


Agosto, 2020 | DOI: 10.1016/j.jcis.2020.03.101

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds


Molina, R; Lalueza, A; Lopez-Santos, C; Ghobeira, R; Cools, P; Morent, R; de Geyter, N; Gonzalez-Elipe, AR
Plasma Processes and Polymers, (2020)
Nanotecnología en Superficies y Plasma

ABSTRACT

Plasma treatment is increasingly being explored as an effective presowing treatment improving seed germination. This study examines the synergetic effect of the irrigation condition and the physicochemical surface properties of wheat seeds subjected to atmospheric dielectric barrier discharge plasma activation on their water uptake and germination. Extensive surface analysis revealed a remarkably enhanced wettability of plasma-treated seeds due to the insertion of oxygen-containing functionalities on their surface. However, long plasma exposures damaged the outermost layers of the pericarp due to a pronounced oxidative etching effect. Although the seed germination capacity was not affected by the plasma treatments, short plasma exposures were shown to enhance water uptake and accelerate seed germination, especially under water-scarcity conditions.


Agosto, 2020 | DOI: 10.1002/ppap.202000086

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