Scientific Papers in SCI

2017


Title: Regenerative Endodontic Procedures: A Perspective from Stem Cell Niche Biology
Author(s): M. Marí-Beffa, J.J. Segura-Egea, A. Díaz-Cuenca
Source: Journal of Endodontics, 43 (2017) 52-62

abstract | fulltext

Introduction

Endodontics uses cell therapy strategies to treat pulpal and periapical diseases. During these therapies, surgeons aim to reconstruct the natural microenvironments that regulate the activity of dental stem cells.

Methods

We searched for more than 400 articles in PubMed using key words from regenerative endodontics and dental stem cell biology. In 268 articles, we reviewed what factors may influence histologic results after preclinical dental treatments that use regenerative endodontic procedures after pulpectomy.

Results

Several factors, such as the origin of stem cells, the biomimicry of scaffolds used, and the size of lesions, are considered to influence the histologic appearance of the regenerated pulp-dentin complex after treatments. Information is accumulating on transcription factors that generate the pulp-dentin complex and survival/trophic factors that would benefit niche recovery and histologic results.

Conclusions

In this article, we discuss the noninterchangeability of stem cells, the influence of dentin-entrapped molecule release on pulp regeneration and survival of stem cells, and the need of positional markers to assess treatments histologically. The ex vivo amplification of appropriate dental stem cells, the search for scaffolds storing the molecular diversity entrapped in the dentin, and the use of positional transcription factors as histologic markers are necessary to improve future preclinical experiments.

January, 2017 | DOI: 10.1016/j.joen.2016.09.011

2016


Title: Perspectives on oblique angle deposition of thin films: From fundamentals to devices
Author(s): Barranco, A; Borras, A; Gonzalez-Elipe, AR; Palmero, A
Source: Progress in Materials Science, 78 (2016) 59-153

abstract | fulltext

The oblique angle configuration has emerged as an invaluable tool for the deposition of nanostructured thin films. This review develops an up to date description of its principles, including the atomistic mechanisms governing film growth and nanostructuration possibilities, as well as a comprehensive description of the applications benefiting from its incorporation in actual devices. In contrast with other reviews on the subject, the electron beam assisted evaporation technique is analyzed along with other methods operating at oblique angles, including, among others, magnetron sputtering and pulsed laser or ion beam-assisted deposition techniques. To account for the existing differences between deposition in vacuum or in the presence of a plasma, mechanistic simulations are critically revised, discussing well-established paradigms such as the tangent or cosine rules, and proposing new models that explain the growth of tilted porous nanostructures. In the second part, we present an extensive description of applications wherein oblique-angle-deposited thin films are of relevance. From there, we proceed by considering the requirements of a large number of functional devices in which these films are currently being utilized (e.g., solar cells, Li batteries, electrochromic glasses, biomaterials, sensors, etc.), and subsequently describe how and why these nanostructured materials meet with these needs. 

March, 2016 | DOI: 10.1016/j.pmatsci.2015.06.003

Title: Unbroken Perovskite: Interplay of Morphology, Electro-optical Properties, and Ionic Movement
Author(s): Correa-Baena, JP; Anaya, M; Lozano, G; Tress, W; Domanski, K; Saliba, M; Matsui, T; Jacobsson, TJ; Calvo, ME; Abate, A; Gratzel, M; Miguez, H; Hagfeldt, A
Source: Advanced Materials, 28 (2016) 5031-5037

abstract | fulltext

Hybrid organic-inorganic perovskite materials have risen up as leading components for light-harvesting applications. However, to date many questions are still open concerning the operation of perovskite solar cells (PSCs). A systematic analysis of the interplay among structural features, optoelectronic performance, and ionic movement behavior for FA(0.83)MA(0.17)Pb(I0.83Br0.17)(3) PSCs is presented, which yield high power conversion efficiencies up to 20.8%.

July, 2016 | DOI: 10.1002/adma.201600624

Title: High-Throughput Fabrication of Resonant Metamaterials with Ultrasmall Coaxial Apertures via Atomic Layer Lithography
Author(s): Yoo, D; Nguyen, NC; Martin-Moreno, L; Mohr, DA; Carretero-Palacios, S; Shaver, J; Peraire, J; Ebbesen, TW; Oh, SH
Source: Nano Letters, 16 (2016) 2040-2046

abstract | fulltext

We combine atomic layer lithography and glancing angle ion polishing to create wafer-scale metamaterials composed of dense arrays of ultrasmall coaxial nanocavities in gold films. This new fabrication scheme makes it possible to shrink the diameter and increase the packing density of 2 nm-gap coaxial resonators, an extreme subwavelength structure first manufactured via atomic layer lithography, both by a factor of 100 with respect to previous studies. We demonstrate that the nonpropagating zeroth-order Fabry-Perot mode, which possesses slow light-like properties at the cutoff resonance, traps infrared light inside 2 nm gaps (gap volume similar to lambda(3)/10(6)). Notably, the annular gaps cover only 3% or less of the metal surface, while open-area normalized transmission is as high as 1700% at the epsilon-near-zero (ENZ) condition. The resulting energy accumulation alongside extraordinary optical transmission can benefit applications in nonlinear optics, optical trapping, and surface-enhanced spectroscopies. Furthermore, because the resonance wavelength is independent of the cavity length and dramatically red shifts as the gap size is reduced, large-area arrays can be constructed with lambda(resonance) >> period, making this fabrication method ideal for manufacturing resonant metamaterials.

March, 2016 | DOI: 10.1021/acs.nanolett.6b00024

Title: Optofluidic Modulation of Self-Associated Nanostructural Units Forming Planar Bragg Microcavities
Author(s): Oliva-Ramirez, M; Barranco, A; Loffler, M; Yubero, F; Gonzalez-Elipe, AR
Source: ACS Nano, 10 (2016) 1256-1264

abstract | fulltext

Bragg microcavities (BMs) formed by the successive stacking of nanocolumnar porous SiO2 and TiO2 layers with slanted, zigzag, chiral, and vertical configurations are prepared by physical vapor deposition at oblique angles while azimuthally varying the substrate orientation during the multilayer growth. The slanted and zigzag BMs act as wavelength-selective optical retarders when they are illuminated with linearly polarized light, while no polarization dependence is observed for the chiral and vertical cavities. This distinct optical behavior is attributed to a self-nanostructuration mechanism involving a fence-bundling association of nanocolumns as observed by focused ion beam scanning electron microscopy in the slanted and zigzag microcavities. The outstanding retarder response of the optically active BMs can be effectively modulated by dynamic infiltration of nano- and mesopores with liquids of different refraction indices acting as a switch of the polarization behavior. The unprecedented polarization and tunable optofluidic properties of these nanostructured photonic systems have been successfully simulated with a simple model that assumes a certain birefringence for the individual stacked layers and accounts for the light interference phenomena developed in the BMs. The possibilities of this type of self-arranged nanostructured and optically active BMs for liquid sensing and monitoring applications are discussed.

January, 2016 | DOI: 10.1021/acsnano.5b06625

Title: Electrocatalytic System for the Simultaneous Hydrogen Production and Storage from Methanol
Author(s): Gonzalez-Cobos, J; Rico, VJ; Gonzalez-Elipe, AR; Valverde, JL; de Lucas-Consuegra, A
Source: ACS Catalysis, 6 (2016) 1942-1951

abstract | fulltext

This paper reports a groundbreaking approach for simultaneous hydrogen production and storage that entails catalysis, electrochemistry, surface science, and materials synthesis. A novel electrocatalytic system is developed based on nickel nanocolumnar films of controlled microstructure prepared on K-βAl2O3 solid electrolyte supports by oblique angle physical vapor deposition. The outstanding characteristics of this system are a hydrogen storage capacity of up to 19 g of H2 (100 g of Ni)−1, which is unparalleled in the literature and the possibility of controlling its release electrochemically, under fixed mild conditions (280 °C and normal pressure). H2 is produced in situ by methanol steam re-forming on the Ni catalyst, and it spills over onto graphene oxide aggregates formed during the catalytic process, as confirmed by SEM, FTIR, and Raman spectroscopy. The proposed storage mechanism considers a synergetic contribution of both Ni and graphene oxide, promoted by K+ ions, in enhancing the hydrogen storage capacity of the system.

March, 2016 | DOI: 10.1021/acscatal.5b02844

Title: Three-Dimensional Optical Tomography and Correlated Elemental Analysis of Hybrid Perovskite Microstructures: An Insight into Defect-Related Lattice Distortion and Photoinduced Ion Migration
Author(s): Galisteo-Lopez, JF; Li, YL; Miguez, H
Source: Journal of Physical Chemistry Letters, 7 (2016) 5227-5234

abstract | fulltext

Organic lead halide perovskites have recently been proposed for applications in light-emitting devices of different sorts. More specifically, regular crystalline microstructures constitute an efficient light source and fulfill the geometrical requirements to act as resonators, giving rise to waveguiding and optical amplification. Herein we show three-dimensional laser scanning confocal tomography studies of different types of methylammonium lead bromide microstructures which have allowed us to dissect their photoemission properties with a precision of 0.036 mu m(3). This analysis shows that their spectral emission presents strong spatial variations which can be attributed to defect-related lattice distortions. It is also largely enhanced under light exposure, which triggers the migration of halide ions away from illuminated regions, eventually leading to a strongly anisotropic degradation. Our work points to the need for performing an optical quality test of individual crystallites prior to their use in optoelectronics devices and provides a means to do so.

December, 2016 | DOI: 10.1021/acsjpclett.6b02456

Title: Investigation of a Pt containing washcoat on SiC foam for hydrogen combustion applications
Author(s): Fernandez, A; Arzac, GM; Vogt, UF; Hosoglu, F; Borgschulte, A; de Haro, MCJ; Montes, O; Zuttel, A
Source: Applied Catalysis B: Environmental, 180 (2016) 336-343

abstract | fulltext

A commercial Pt based washcoat, used for catalytic methane combustion, was studied supported on a commercial SiC foam as catalytic material (Pt/SiC) for catalytic hydrogen combustion (CHC). Structural and chemical characterization was performed using Electron Microscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The reaction was monitored following water concentration by Fourier Transform Infrared spectra (FTIR). The FTIR method was compared with H2 detection by Gas Cromatography (GC) and has shown to be adequate to study the kinetics of the CHC reaction in steady state under our experimental conditions (very lean 1% (v/v) H2/air mixtures). The catalyst is composed of 5–20 nm disperse Pt nanoparticles decorating a mixture of high surface area Al2O3 and small amounts of ceria supported on the SiC foam which also contains alumina as binder. The Pt/SiC catalytic material has demonstrated to be active enough to start up the reaction in a few seconds at room temperature. The material has been able to convert at least 18.5 Lhydrogen min−1 gPt−1 at room temperature in conditions of excess of catalyst. The Pt/SiC material was studied after use using XPS and no significant changes on Pt oxidation states were found. The material was characterized from a kinetic point of view. From the conversion-temperature plot a T50(temperature for 50% conversion) of 34 °C was obtained. Activation energy measured in our conditions was 35 ± 1 kJ mol−1.

January, 2016 | DOI: 10.1016/j.apcatb.2015.06.040

Title: O-2-assisted Water Gas Shift reaction over structured Au and Pt catalysts
Author(s): Gonzalez-Castano, M; Reina, TR; Ivanova, S; Tejada, LMM; Centeno, MA; Odriozola, JA
Source: Applied Catalysis B: Enviromental, 185 (2016) 337-343

abstract | fulltext

Platinum and gold structured catalysts were compared as active phases in classical and O2-assisted Water Gas Shift (WGS) reaction. Both metals were supported on iron-doped ceria mixed oxide and then, structured on metallic micromonolithic devices. As expected the WGS activity of both micromonoliths is conditioned by the nature of the noble metals being Pt the most active metal in traditional conditions. However, the addition of oxygen to the classical water gas feed turns the balance in favor of the gold based catalysts, being the presence of gold responsible for an excessive improvement of the catalytic activity.

May, 2016 | DOI: 10.1016/j.apcatb.2015.12.032

Title: Cascade charge separation mechanism by ternary heterostructured BiPO4/TiO2/g-C3N4 photocatalyst
Author(s): Obregon, S; Zhang, YF; Colon, G
Source: Applied Catalysis B: Enviromental, 184 (2016) 96-103

abstract | fulltext

A complex ternary BiPO4/TiO2/gC(3)N(4) heterostructure has been obtained from a simple impregnation method having good photoactivities for the degradation of phenol under solar-like irradiation. From the wide structural, surface and electronic characterization, we have stated that the formation of the ternary heterojunction notably affect photoactivity of pristine TiO2. Thus, the best result for the binary system was obtained for 70 wt%TiO2-30 wt% BiPO4 system. The incorporation of gC(3)N(4) leads to a further improvement on the photocatalytic activity when it is specifically done over TiO2. By means of photoluminescence spectroscopy and reactive oxygen species formation test, we propose that the effective charge carrier separation is taking place through a cascade-driven electronic mechanism. Therefore, by choosing the adequate band-engineering tailoring an important improved photoactivity can be achieved. 

May, 2016 | DOI: 10.1016/j.apcatb.2015.11.027

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