Materiales Funcionales Nanoestructurados

Early results on the plasma deposition of dielectric thin films on acoustic wave (AW) activated substrates revealed a densification pattern arisen from the focusing of plasma ions and their impact on specific areas of the piezoelectric substrate. Herein, we extend this methodology to tailor the plasma deposition of metals onto AW-activated LiNbO₃ piezoelectric substrates. Our investigation reveals the tracking of the initial stages of nanoparticle (NP) formation and growth during the submonolayer deposition of silver. We elucidate the specific role of AW activation in reducing particle size, enhancing particle circularity, and retarding NP agglomeration and account for the physical phenomena making these processes differ from those occurring on non-activated substrates. We provide a comparative analysis of the results obtained under two representative plasma conditions: diode DC sputtering and magnetron sputtering. In the latter case, the AW activation gives rise to a 2D pattern of domains with different amounts of silver and a distinct size and circularity for the silver NPs. This difference was attributed to the specific characteristics of the plasma sheath formed onto the substrate in each case. The possibilities of tuning the plasmon resonance absorption of silver NPs by AW activation of the sputtering deposition process are discussed.

The development of efficient strategies to tune the CO2RR selectivity of Cu-based catalytic interfaces, especially on specific domains, such as Cu (200) facets with high activity toward competitive hydrogenation evolution reaction (HER), remains a challenging task. In this work, Cu-based catalytic layers with thiocyanate (-SCN), cyanide (-CN), or ethylenediamine (-NH2R) coordination linkages are prepared on Cu nanocolumns arrays (Cu NCAs) with predominant (200) exposed facets. The coordination of these ligands induces more Cu+ species and inhibits the adsorption of H & lowast; on the Cu (200) facet, leading to enhanced CO2RR performance and substantially suppressing the competitive HER. The faradaic efficiency (FE) of Cu-SCN, Cu-CN, and Cu-NH2R NWAs for producing HCOOH, C2H4, and C1 mixture products (HCOOH and CO) reach to 66.5%, 21.1%, and 57.1%, respectively. In situ spectroscopic studies reveal Cu-SCN, Cu-CN, and Cu-NH2R exhibit more reasonable adsorption energy toward & lowast;OCHO, *CO, and *COOH intermediates, promoting the HCOOH, C2H4, and C1 mixture generation, respectively. This study might provide a new perspective for the development of high-performance Cu-based CO2RR catalytic electrodes based on the combination of various commercial free-standing Cu substrates and organic/inorganic ligands. (c) 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The ability to control the porosity of thin oxide films is a key factor determining their properties. Despite the abundance of dry processes for synthesizing oxide porous layers, a high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultraporous titanium dioxide thin films at room or mild temperatures (T <= 120 degrees C) by a sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85% that are comparable to those of advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures, presenting a distribution of anatase clusters embedded in the sponge-like open porous structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees C in air, which increases the fraction of embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive, becoming superhydrophilic when subjected to ultraviolet light irradiation. The supported, percolated, and nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel-like film thickness, which reaches efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and applicable to ultrahigh porous conformal oxides of different compositions, with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.

The rapid growth of global energy consumption and the increasing demand for sustainable and renewable energy sources have urged vast research into harnessing energy from various sources. Among them, the most promising approaches are nanogenerators (NGs) and solar cells (SCs), which independently offer innovative solutions for energy harvesting. This review paper presents a comprehensive analysis of the integration of NGs and SCs, exploring advanced hybrid structures and their diverse applications. First, an overview of the principles and working mechanisms of NGs and SCs is provided for seamless hybrid integrations. Then, various design strategies are discussed, such as piezoelectric and triboelectric NGs with different types of SCs. Finally, a wide range of applications are explored that benefit from the synergistic integration of NGs and SCs, including self-powered electronics, wearable devices, environmental monitoring, and wireless sensor networks. The potential for these hybrid systems is highlighted to address real-world energy needs and contribute to developing sustainable and self-sufficient technologies. In conclusion, this review provides valuable insights into the state-of-the-art developments in NGs and SCs integration, shedding light on advanced hybrid structures and their diverse applications.

Stainless steel (SS) alloys are prevalent in many industries, household appliances or other commodities, where a strict control of surface properties is required to tailor their interaction with the environment. In this work we report a new procedure of stainless steel surface processing that provides a multifunctional response including superhydrophobicity, omniphobicity, self-cleaning, anti-fouling and effective anti-icing capacity, while still preserving a corrosion resistance similar to that of this material in compact form. The method consists of a first nanostructuration step followed by a low fluorination. The nanostructured surfaces presented a dual scale roughness of hierarchical character. The liquid free approach developed in this work to get this singular surface nanostructuration entails a first laser treatment of stainless steel flat substrates, followed by the deposition of a nanostructured thin layer of this material by electron beam evaporation in an oblique angle configuration. The resulting hierarchical surfaces were subjected to fluorination by: (i) the plasma-assisted deposition of a thin Teflon-like coating or (ii) the grafting of fluorinated molecules. The self-cleanable, anti-adherent and ice repellent character of the resulting low fluorinated surfaces outperformed the behaviour of classical slippery surfaces obtained by the infusion of high amounts of fluorinated liquids. These hierarchical SS surfaces withstood mild abrasion tests and the effect of water jets. Moreover, the corrosion behaviour of the fluorinated surfaces determined through their potentiodynamic analysis revealed a similar corrosion resistance than the flat SS substrates. Outstandingly, after these corrosion tests, the fluorinated samples obtained by grafting preserved their surface functionalities without significant degradation. The high mechanical and chemical stability of these low fluorinated samples support their usage for a large variety of applications.

The effect of applying a negative bias during deposition of a previously designed multilayer solar selective absorber coating was studied on two types of substrates (316L stainless steel and Inconel 625). The solar selective coating is composed of different chromium aluminum nitride layers deposited using a combination of radiofrequency (RF), direct current (DC), and high-power impulse magnetron sputtering (HiPIMS) technologies. The chemical composition is varied to generate an infrared reflective/absorber layer (with low Al addition and N vacancies) and two CrAlN intermediate layers with medium and high aluminum content (Al/Cr = 0.6 and 1.2). A top aluminum oxide layer (Al₂O₃) is deposited as an antireflective layer. In this work, a simultaneous DC-pulsed bias (−100 V, 250 kHz) was applied to the substrates in order to increase the film density. The optical performance, thermal stability, and oxidation resistance was evaluated and compared with the performance obtained with similar unbiased coating and a commercial Pyromark paint reference at 600, 700, and 800 °C. The coating remained stable after 200 h of annealing at 600 °C, with solar absorptance (α) values of 93% and 92% for samples deposited on stainless steel and Inconel, respectively, and a thermal emittance ε_25°C of 18%. The introduction of additional ion bombardment during film growth through bias assistance resulted in increased durability, thermal stability, and working temperature limits compared with unbiased coatings. The solar-to-mechanical energy conversion efficiency at 800 °C was found to be up to 2 times higher than Pyromark at C = 100 and comparable at C = 1000.

Hybrid materials based on calcium phosphates and synthetic polymers can potentially be used for caries protection due to their similarity to hard tissues in terms of composition, structure and a number of properties. This study is focused on the biomimetic synthesis of hybrid materials consisting of hydroxiapatite and the zwitterionic polymers polysulfobetaine (PSB) and polycarboxybetaine (PCB) using controlled media conditions with a constant pH of 8.0–8.2 and Ca/P = 1.67. The results show that pH control is a dominant factor in the crystal phase formation, so nano-crystalline hydroxyapatite with a Ca/P ratio of 1.63–1.71 was observed as the mineral phase in all the materials prepared. The final polymer content measured for the synthesized hybrid materials was 48–52%. The polymer type affects the final microstructure, and the mineral particle size is thinner and smaller in the synthesis performed using PCB than using PSB. The final intermolecular interaction of the nano-crystallized hydroxyapatite was demonstrated to be stronger with PCB than with PSB as shown by our IR and Raman spectroscopy analyses. The higher remineralization potential of the PCB-containing synthesized material was demonstrated by in vitro testing using artificial saliva.

The aim of this work is to review the application of bioceramic materials in the context of current regenerative dentistry therapies, focusing on the latest advances in the synthesis of advanced materials using the sol–gel methodology. Chemical synthesis, processing and therapeutic possibilities are discussed in a structured way, according to the three main types of ceramic materials used in regenerative dentistry: bioactive glasses and glass ceramics, calcium phosphates and calcium silicates. The morphology and chemical composition of these bioceramics play a crucial role in their biological properties and effectiveness in dental therapeutics. The goal is to understand their chemical, surface, mechanical and biological properties better and develop strategies to control their pore structure, shape, size and compositions. Over the past decades, bioceramic materials have provided excellent results in a wide variety of clinical applications related to hard tissue repair and regeneration. Characteristics, such as their similarity to the chemical composition of the mineral phase of bones and teeth, as well as the possibilities offered by the advances in nanotechnology, are driving the development of new biomimetic materials that are required in regenerative dentistry. The sol–gel technique is a method for producing synthetic bioceramics with high purity and homogeneity at the molecular scale and to control the surfaces, interfaces and porosity at the nanometric scale. The intrinsic nanoporosity of materials produced by the sol–gel technique correlates with the high specific surface area, reactivity and bioactivity of advanced bioceramics.

A model is presented giving the mean dimensions of acicular octadecahedral microcrystallites of a rutile titanium dioxide powder. Reduction at 823 K, in conjunction with ESR, electrical conductivity and controlled re-oxidation has enabled the model to be applied to reduced microcrystallites. At 300 K they contain <0.1% of paramagnetic [Ti^3+↑ V_O: ^↑Ti³⁺] reduced edge sites and >99.9% of reduced spin-paired [Ti^3+↑↓ Ti³⁺ V_O:] sites. These sites are situated on the external crystal faces and on polygonal bulk crystallographic shear (CS) structures inclined to the microcrystal four-fold symmetry axis. CS structures are quantum-sized [Ti₄O₇V_O:] environments which broaden the paramagnetic signals at 78 K. Temperature programmed reduction in H₂(g) reveals atomic hydrogen as a precursor to CS structure formation via a lattice template formed on microcrystallite faces. Shear structures are oxidised on their polygonal perimeters at differing rates on the respective microcrystallite faces by anionic vacancy transfer from sub-surface regions.

In this work, we have prepared a series of Pd catalysts on a CNx support for the liquid phase decomposition of formic acid. The structured CNx support was obtained through thermal pyrolysis of melamine foam and the pyrolysis conditions were optimized to achieve high surface area. The resulting support contains high amount of nitrogen with a contribution of pyridinic component. Several Pd catalysts were prepared and under optimized condi-tions, we were able to obtain small (2.7 +/- 0.9) nm Pd particles by using the oxidized support in powdery form. The activity of the optimized catalyst was studied under different con-ditions in the fresh and the used form. The fresh catalyst did not show significant activity. However, we found that the catalyst activated after use. Activation was understood in terms of the variation of surface Pd oxidation states under the effect of formic acid/sodium formate solutions. We found that the best activity is achieved under an optimal proportion of Pd0/PdII surface states according to previous reports. Under the best conditions, the activity of the best catalyst (8.6Pd/CN0.3) was as high as 9245 h-1, attributable to the small particle size, the Pd0/PdII ratio, the amount of pyridinic nitrogen, and the testing conditions, which included the preadsorption of sodium formate

Plasma reactions of CO2 + CH4 mixtures have been proposed as a suitable process for the dry reforming of methane. Without specific catalysts, most studies report the formation of CO and H2 as main reaction products and arise the question whether CHx radicals coming from CH4 may interact with intermediate species formed by electron impact dissociation of CO2, a critical step for the formation of high added value oxygenated compounds. We have addressed this question studying the CO2 + CH4 plasma reaction in a ferroelectric-moderated packed -bed reactor varying the reactants ratio. Analysis of the reaction products by mass spectrometry and the plasma reaction intermediates by optical emission spectroscopy suggest that few direct cross-link interactions exist between intermediate plasma species issued from CH4 or CO2. This preliminary evidence is corroborated by experiments using 13CO2 instead 12CO2 as reactant. The isotope labeling procedure has proved that plasma re-action mechanisms of CO2 and CH4 molecules proceed almost independently, with the formation of small amounts of water and the removal of carbon deposits resulting CH4 plasma decomposition as sole evidences of cross reactions. These results highlight the need of using catalysts to promote specific surface reactions for a better control of the selectivity of the process.

Numerous works have demonstrated that cold plasma treatments constitute an effective procedure to accelerate seed germination under nonstress conditions. Evidence also exists about a positive effect of plasmas for germination under environmental stress conditions. For barley seeds, this work studies the influence of cold plasma treatments on the germination rate and initial stages of plant growth in common stress environments, such as drought, salinity, and low-temperature conditions. As a general result, it has been found that the germination rate was higher for plasma-treated than for untreated seeds. Plasma also induced favorable changes in plant and radicle dimensions, which depended on the environment. The obtained results demonstrate that plasma affects the biochemical metabolic chains of seeds and plants, resulting in changes in the concentration of biochemical growing factors, a faster germination, and an initially more robust plant growth, even under stress conditions. These changes in phenotype are accompanied by differences in the concentration of biomarkers such as photosynthetic pigments (chlorophylls a and b and carotenoids), reactive oxygen species, and, particularly, the amino acid proline in the leaves of young plants, with changes that depend on environmental conditions and the application of a plasma treatment. This supports the idea that, rather than an increase in seed water imbibition capacity, there are clear beneficial effects on seedling of plasma treatments.

Although titanium is widely used as biomaterial, the control of the interface properties between its surface and the surrounding physiological environment (like bone, other tissues or biofluids) results crucial to achieve a successful osseointegration and good biomechanical and functional performance. In this work, commercially pure titanium (Grade IV) discs obtained by conventional powder metallurgy were coated with 1-3 mu m of Ti6Al4V (Grade V) alloy using DC-pulsed or high-power impulse magnetron sputtering (HiPIMS) technique with the aim of improving their biomedical performance. SEM, confocal microscopy, X-ray dif-fraction, nanoindentation and wetting measurements are used to evaluate the bio-interface role of the titanium-coated implants. Conformal Ti6Al4V coatings with controlled nano-roughness can be deposited with enhanced mechanical (H = 5-8 GPa; E = 140-160 GPa) and hydrophobic properties thanks to a dense columnar structure. The increased Ti-O bonding at the interface helps to prevent the corrosion due to the formation of a surface passivation layer. Particularly in the case of the HiPIMS process, the surface mod-ification of titanium implants (chemistry, morphology and structure) appears as an effective strategy for satisfying the biomedical requirements and functionality, with enhanced mechanical properties and na-nostructuration for prevention of bacteria colonization.

The development of anti-icing robust surfaces is a hot topic nowadays and particularly crucial in the aeronautics or wind energy sectors as ice accretion can compromise safety and power generation efficiency. However, the current performance of most anti-icing strategies has been proven insufficient for such demanding applications, particularly in large unprotected zones, which located downstream from thermally protected areas, may undergo secondary icing. Herein, a new testing methodology is proposed to evaluate accretion mechanisms and secondary icing phenomena through, respectively, direct impact and running-wet processes and systematically applied to anti-icing materials including commercial solutions and the latest trends in the state-of-the-art. Five categories of materials (hard, elastomeric, polymeric matrix, SLIPS and superhydrophobic) with up to fifteen formulations have been tested. This Round-Robin approach provides a deeper understanding of anti-icing mechanisms revealing the strengths and weaknesses of each material. The conclusion is that there is no single passive solution for anti-ice protection. Thus, to effectively protect a given real component, different tailored materials fitted for each particular zone of the system are required. For this selection, shape analysis of such a component and the impact characteristics of water droplets under real conditions are needed as schematically illustrated for aeronautic turbines.

The morphology and void connectivity of thin films grown by a magnetron sputtering deposition technique at oblique geometries were studied in this paper. A well-tested thin film growth model was employed to assess the features of these layers along with experimental data taken from the literature. A strong variation in the film morphology and pore topology was found as a function of the growth conditions, which have been linked to the different collisional transport of sputtered species in the plasma gas. Four different characteristic film morphologies were identified, such as (i) highly dense and compact, (ii) compact with large, tilted mesopores, (iii) nanocolumns separated by large mesopores, and (iv) vertically aligned sponge-like coalescent nanostructures. Attending to the topology and connectivity of the voids in the film, the nanocolumnar morphology was shown to present a high pore volume and area connected with the outside by means of mesopores, with a diameter above 2 nm, while the sponge-like nanostructure presented a high pore volume and area, as well as a dense network connectivity by means of micropores, with a diameter below 2 nm. The obtained results describe the different features of the porous network in these films and explain the different performances as gas or liquid sensors in electrochromic applications or for infiltration with nanoparticles or large molecules.

Enabling active de-icing functionality on low heat conductive and transparent materials is a requirement for several seminal industries in critical economic sectors. However, developing efficient and environmentally friendly de-icing methods still fails because of compatibility problems with large-scale devices and real-world conditions. In this paper, de-icing several square centimeters covered with thick layers of glaze ice is approached through nanoscale activation by surface acoustic waves (SAWs). De-icing functionality is demonstrated with a self-supported piezoelectric material (LiNbO3) and a piezoelectric film (ZnO) deposited on fused silica, the latter system proving the compatibility of the method with materials of practical relevance. Its applicability to large and transparent substrates is demonstrated by placing the interdigitated electrodes (IDTs) required for activation close to the substrate's edges, leaving most of the surface unaltered. The de-icing mechanism of glaze ice by SAW activation is revealed by simulating the SAW propagation on ice-covered surfaces and by experimental analysis of the ice melting process. This involves a combination of ice mechanical stress activation and heating through the initially formed water/ice front. Possible Joule effects due to ohmic losses in the IDTs have been discarded, monitoring local temperature variations during SAW activation at and out of resonance conditions.

Bismuth oxide (Bi2O3) coatings and composite coatings containing this oxide have been studied due to their potential applications in gas sensing, optoelectronics, photocatalysis, and even tribology. Two parametric models based on chemical features have been proposed with the aim of predicting the lubricity response of oxides. However, such models predict contradictory values of the coefficient of friction (COF) for Bi2O3. In this study, we deposited Bi2O3 coatings, via magnetron sputtering, on AISI D2 steel substrates to evaluate the tribological responses of the coatings and determine which parametric model describes them better. Experimentally, only coatings presenting the cubic defective fluorite-like delta-Bi2O3 phase could be evaluated. We performed pin-on-disk tests at room temperature and progressively increasing temperatures up to 300 degrees C using alumina and steel counter-bodies. Low wear and COFs (0.05 to 0.15) indicated that the delta-phase behaves as a lubricious solid, favoring the validity of one of the models. An alternative explanation is proposed for the low COF of the defective fluorite-like structure since it is well known that it contains 25% of anionic vacancies that can be ordered to form low shear-strength planes, similar to the Magneli phases. Two challenges for future potential applications were observed: one was the low adhesion strength to the substrate, and the other was the thermal stability of this phase.

Natural polymers such as cellulose have interesting tribo- and piezoelectric properties for paper-based energy harvesters, but their low performance in providing sufficient output power is still an impediment to a wider deployment for IoT and other low-power applications. In this study, different types of celluloses were combined with nanosized carbon fillers to investigate their effect on the enhancement of the electrical properties in the final nanogenerator devices. Cellulose pulp (CP), microcrystalline cellulose (MCC) and cellulose nanofibers (CNFs) were blended with carbon black (CB), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). The microstructure of the nanocomposite films was characterized by scanning electron and probe microscopies, and the electrical properties were measured macroscopically and at the local scale by piezoresponse force microscopy. The highest generated output voltage in triboelectric mode was obtained from MCC films with CNTs and CB, while the highest piezoelectric voltage was produced in CNF-CNT films. The obtained electrical responses were discussed in relation to the material properties. Analysis of the microscopic response shows that pulp has a higher local piezoelectric d(33) coefficient (145 pC/N) than CNF (14 pC/N), while the macroscopic response is greatly influenced by the excitation mode and the effective orientation of the crystals relative to the mechanical stress. The increased electricity produced from cellulose nanocomposites may lead to more efficient and biodegradable nanogenerators.

Reactive multilayer systems are nanostructures of great interest for various technological applications because of their high energy release rate during the self-propagating reaction of their components. Therefore, many efforts are aimed at controlling the propagation velocity of these reactions. Herein, reactive multilayer systems of Al/Ni in the shape of free-standing foils with a wavelike surface morphology prepared by using sacrificial substrates with well-aligned waves are presented and the propagation of the reaction along different directions of the reproduced waves is analyzed. During the ignition test, the propagation front is recorded with a high-speed camera, and the maximum temperature is measured using a pyrometer. The propagation of the reaction is favored in the direction of the waves, which points out the influence of the anisotropy generated by this morphology and how it affects the propagation dynamics and the resulting microstructure. Furthermore, compared to their counterparts fabricated on flat substrates, these reactive multilayers with wavelike morphology exhibit a remarkable reduction in the propagation velocity of the reaction of about 50%, without significantly affecting the maximum temperature registered during the reaction.

Plasma-catalysis has been proposed as a potential alternative for the synthesis of ammonia. Studies in this area focus on the reaction mechanisms and the apparent synergy existing between processes occurring in the plasma phase and on the surface of the catalytic material. In the present study, we approach this problem using a parallel-plate packed-bed reactor with the gap between the electrodes filled with pellets of lead zirconate titanate (PZT), with this ferroelectric material modified with a coating layer of alumina (i.e., Al₂O₃/PZT) and the same alumina layer incorporating ruthenium nanoparticles (i.e., Ru-Al₂O₃/PZT). At ambient temperature, the electrical behavior of the ferroelectric packed-bed reactor differed for these three types of barriers, with the plasma current reaching a maximum when using Ru-Al₂O₃/PZT pellets. A systematic analysis of the reaction yield and energy efficiency for the ammonia synthesis reaction, at ambient temperature and at 190 °C and various electrical operating conditions, has demonstrated that the yield and the energy efficiency for the ammonia synthesis do not significantly improve when including ruthenium particles, even at temperatures at which an incipient catalytic activity could be inferred. Besides disregarding a net plasma-catalysis effect, reaction results highlight the positive role of the ferroelectric PZT as moderator of the discharge, that of Ru particles as plasma hot points, and that of the Al₂O₃ coating as a plasma cooling dielectric layer.

This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material.

The main raw material for manufacture of paper is cellulose fibers that can be virgin or recycled. Globally, 70% of the Tetra Pak packages sold are not recycled and remain as unused wastes. Therefore, the development of alternatives to promote greater recycling and sustainable use of these packages is of great interest. In this study, the formation of precipitated calcium carbonates (PCC) in the presence of carboxymethyl cellulose (CMC) is studied at different temperatures, and the morphologically diverse particles obtained are explored as filler for composites based on cellulosic fibers recovered from Tetra Pak containers. It was found that the addition of filler does not lead to deterioration of either tensile strength or thermal and stability of the obtained composite samples. Results also suggest that the morphological diversity of the filler contributes to a more efficient filling of the interfibrillar spaces of cellulosic fibers and, in turn, to the fiber and filler compatibility.

The sol-gel process is a wet chemical technique that allows very fine control of the composition, microstructure, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. In this work, the influence of different sol-gel synthesis variables on the preparation of endodontic cement based on calcium silicate with Ca/Si stoichiometry equal to 3 was studied. Starting from the most optimal hydraulic composition selected, a novel second post-synthesis treatment using ethanol was essayed. The effects of the tested variables were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption, and Gillmore needles to determine the setting time and simulated body fluid (SBF) immersion to measure the bioactive response in vitro. The results indicated that the sol-gel technique is effective in obtaining bioactive endodontic cements (BECs) with high content of the hydraulic compound tricalcium silicate (C3S) in its triclinic polymorph. The implementation of a novel post-synthesis treatment at room temperature using ethanol allows obtaining a final BEC product with a finer particle size and a higher CaCO3 content, which results in an improved material in terms of setting time and bioactive response.

This work is carried out in the context of the anion exchange membrane water electrolysis (AEMWE) and pursuits to determine the influence of different cell components on the global electrochemical performance. Ionomer-free electrodes consisting of anodic Ni-Fe and cathodic Ni electrocatalysts deposited by magnetron sputtering in an oblique angle deposition configuration were utilized for this study. In addition to the characteristics and equivalent thickness of the electrocatalysts, other factors affecting the efficiency that have been considered in this study encompass the type of gas diffusion layer (GDLs), including carbon paper and stainless-steel fiber paper supports, and several commercial anion exchange membranes. The electrocatalytic performances in both a threeelectrode and complete single cell AEMWE set-ups, together with the physico-chemical characterization of the electrodes before and after operation, have served to select the optimum components for the utilized cell configuration. Thus, current densities of 670 mA cm-2, at polarization voltage of 2.2 V, 1.0 M KOH electrolyte and 40 degrees C were obtained in a membrane electrode assembly. A seven days chronopotentiometry experiment at a fixed current of 400 mA cm-2 demonstrated a noticeable stability of this type of AEMWE cells incorporating ionomer-free electrodes.

Bloch surface waves sustained by truncated 1D photonic crystals (1DPCs) are well known tools for surface-enhanced spectroscopy. They provide strongly confined fields with uniform distribution over a large surface area, a characteristic exploited in standard refractometric sensing. However, their application to polarization-sensitive investigations is not straightforward because the transverse electric (TE) and magnetic (TM) surface modes possess distinct dispersion relations, therefore their relative phase is not conserved along propagation and the polarization state of any wave obtained by combining these modes is ill-defined. In this work, a novel design of a 1DPC is realized in which the TE and TM modes exhibit the same phase velocity over a broadband spectral range and thus their dispersion relations overlap. The capability to simultaneously excite TE and TM modes with a well-defined phase relation allows the generation of surface waves with a controlled polarization state. This paves the way to polarization-resolved surface-enhanced analysis, including, for example, linear and circular dichroism spectroscopy of grafted molecular layers at the photonic crystal surface.

Stainless steel (SS), widely used because of its outstanding corrosion protection properties, does not possess any particular anti-stain or anti-bacterial activity as required for household and sanitary applications. This work reports the fabrication of SS thin films that, keeping a similar corrosion resistance than the bulk material, presents hydrophobicity and anti-bacterial activity. These thin films are prepared at ambient temperature by physical vapor deposition (PVD), either electron beam evaporation (EBE) or magnetron sputtering (MS), at oblique angles (OAD). According to their scanning electron microcopy and atomic force microscopy analysis, the microstructure of the OAD-SS thin films consisted of tilted and separated nanocolumns defining a surface topology that, characterized by a high percentage of void space, varied with the deposition conditions and procedure, either EBE or MS. It has been shown that particularly the nanocolumnar MS-OAD thin films preserved and even improved the high corrosion resistance of compact SS, as determined by electrochemical analysis. Besides, all OAD-SS thin films depict hydrophobicity and a high antibacterial activity. These features, particularly remarkable for the MS-OAD thin films, have been related with their tip-like termination at the surface and the existence of large void spaces separating the nanocolumns. This topology appears to affect negatively the bacteria's deployment onto the surface and therefore the survival rate. Differences in the corrosion and antibacterial performance between EBE and MS-OAD thin films have been related with the specificities of these two PVD methods of thin film preparation. A relatively high abrasion resistance, as determined by abrasion tests, supports the use of MS-OAD thin films for the protection of commodity materials.

Light trapping effects are known to boost the photocatalytic degradation of organic molecules in 3D photonic structures of anatase titania (a-TiO2) with an inverse opal configuration. In the present work, we show that photocatalytic activity can also be enhanced in a-TiO2 thin films if they are incorporated within a nanoporous 1D optical resonant microcavity. We have designed and manufactured multilayer systems that, presenting a high open porosity to enable a straightforward diffusion of photodegradable molecules, provide light confinement effects at wavelengths around the absorption edge of photoactive a-TiO2. In brief, we have observed that a nanoporous 1D Bragg microcavity prepared by electron beam evaporation at oblique angles comprising a central defect layer of nanoporous a-TiO2 boosts the photocatalytic degradation of nitrobenzene and methyl orange dye solutions. The multilayer structure of the microcavity was designed to ensure the appearance of optical resonances at the a-TiO2 layer location and wavelengths around the absorption onset of this semiconductor. In this porous 1D Bragg microcavity, the diffusion constraints of molecules through the capping layers covering the a-TiO2 are effectively compensated by an increase in the photocatalytic activity due to the light confinement phenomena. We also report that the absorption coefficient of methyl orange dye solution infiltrated within the pore structure of the microcavity is exalted at the wavelengths of the corresponding optical resonances. This effect gives rise to a small but non-negligible visible light photodegradation of dye molecules. The possibilities of tailoring the design of 1D photonic systems to boost the photocatalytic activity of a-TiO2 are discussed.

Bone resorption and inadequate osseointegration are considered the main problems of titanium implants. In this investigation, the texture and surface roughness of porous titanium samples obtained by the space holder technique were modified with a femtosecond Yb-doped fiber laser. Different percentages of porosity (30, 40, 50, and 60 vol.%) and particle range size (100-200 and 355-500 mu m) were compared with fully-dense samples obtained by conventional powder metallurgy. After femtosecond laser treatment the formation of a rough surface with micro-columns and micro-holes occurred for all the studied substrates. The surface was covered by ripples over the micro-metric structures. This work evaluates both the influence of the macro-pores inherent to the spacer particles, as well as the micro-columns and the texture generated with the laser, on the wettability of the surface, the cell behavior (adhesion and proliferation of osteoblasts), micro-hardness (instrumented micro-indentation test, P-h curves) and scratch resistance. The titanium sample with 30 vol.% and a pore range size of 100-200 mu m was the best candidate for the replacement of small damaged cortical bone tissues, based on its better biomechanical (stiffness and yield strength) and biofunctional balance (bone in-growth and in vitro osseointegration).

This study examined the effects of the cationic ratio of Bi3+/Fe3+ via X-ray photoelectron spectroscopy (XPS) on the magnetic and multiferroic properties of BiFeO3 nanoparticles synthesized using a sonochemical-assisted method. X-ray diffraction revealed the successful synthesis of single-phase BiFeO3 powder after annealing the sonicated material at 723 K. The powder was composed of agglomerates of rounded particles with a mean particle size of 35 nm. XPS was performed to determine the Bi3+/Fe3+ ratio as a function of the heat treatment process and its relationship with secondary phases, which can modulate the magnetic properties of the nano powders. The cationic ratio obtained by XPS confirmed that the powders obtained at 623 and 923 K have excess Bi3+ and Fe3+, respectively, which induces the formation of Bi24Fe2O39 and Bi2Fe4O9 as the majority phases. Powder annealing at 723 K revealed a ferromagnetic order with specific magnetization of 1.8 Am-2/kg. This ferromagnetic behavior was preserved after applying spark plasma sintering (SPS) at 923 K. By contrast, conventional sintering at 1023 K promotes antiferromagnetic order. In addition, the dielectric properties of the ceramic material of the sintered powders showed a behavior related to a typical ferroelectric material.

We present the user-friendly and freely available software package QUEELS (QUantitative analysis of Electron Energy Losses at Surfaces) that allows to calculate effective inelastic scattering cross sections within the dielectric response description, for swift electrons travelling nearby surfaces in several environments. We briefly describe the underlying theoretical models and illustrate its use to evaluate the distribution of energy losses taking place in electron spectroscopies like transmission electron energy loss spectroscopy (TEELS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS), which are widely used for material analysis. This includes the intrinsic excitations due to the core hole in XPS and AES.

A bottleneck for the deployment of the Anion Exchange Membrane Water Electrolysis (AEMWE) is the manufacturing of efficient and long lasting anodes and cathodes for the cells. Highly performant bimetallic Ni/Fe catalyst films with various atomic ratios have been prepared by magnetron sputtering in an oblique angle configuration (MS-OAD) and used as anodes for AEMWE. Electrocatalytic experiments in a small three-electrode cell and a thorough analysis of the electrode properties with various physico-chemical characterization tech-niques have been used to select the nanostructured anode catalyst which, depicting an optimized Ni/Fe ratio, presents the maximum activity for the oxygen evolution reaction. These anode layers are then scale-up for their integration in an AEMWE cell where the influence of assembly conditions and the effect of adding an ionomer to the anodes have been studied. The obtained results have demonstrated the outstanding properties of the fabri-cated bimetallic films in terms of activity, stability, and operation under ionomer-free conditions. Current density values around 400 and 600 mA cm(-2) at 40??& nbsp;and 60 C (2.0 V), respectively, much higher than those obtained with pure Ni, were obtained with an optimized membrane electrode assembly. The high yield obtained with these electrodes gains further relevance when considering that the current yield per unit mass of the anodic active phase catalyst (i.e., 1086 mA mg(-1) at 2.0 V and 40??) is the highest among equivalent values reported in literature. The possibilities and prospects of the use of bimetallic catalyst films prepared by MS-OAD for AEMWE are discussed.

The opto-electronic properties of small-molecules and functional dyes usually differ when incorporated into solid matrices with respect to their isolated form due to an aggregation phenomenon that alters their optical and fluorescent properties. These spectroscopic modifications are studied in the framework of the exciton theory of aggregates, which has been extensively applied in the literature for the study of molecular aggregates of the same type of molecules (homoaggregation). Despite the demonstrated potential of the control of the heteroaggregation process (aggregation of different types of molecules), most of the reported works are devoted to intramolecular aggregates, complex molecules formed by several chromophores attached by organic linkers. The intramolecular aggregates are specifically designed to hold a certain molecular structure that, on the basis of the exciton theory, modifies their optical and fluorescent properties with respect to the isolated chromophores that form the molecule. The present article describes in detail the incorporation of Rhodamine 6G (Rh6G) and 800 (Rh800) into polymeric matrices of poly-(methyl methacrylate), PMMA. The simultaneous incorporation of both dyes results in an enhanced fluorescent emission in the near-infrared (NIR), originating from the formation of ground-state Rh6G-Rh800 intermolecular heteroaggregates. The systematic control of the concentration of both rhodamines provides a model system for the elucidation of the heteroaggregate formation. The efficient energy transfer between Rh6G and Rh800 molecules can be used as wavelength shifters to convert effectively the light from visible to NIR, a very convenient wavelength range for many practical applications which make use of inexpensive commercial detectors and systems.

Carbon dioxide decomposition is a challenging target to combat climate change. Nonthermal plasmas are advantageous for this purpose because they operate at ambient conditions and can be easily scaled-up. In this study, we attempt the CO2 splitting into CO and O-2 in a parallel plate packed-bed plasma reactor moderated with Lead Zirconate Titanate (PZT) as fermelectric component, achieving conversion rates and energy efficiencies higher than those obtained with BaTiO3 in our experimental device. The analysis of the reaction mechanisms with optical emission spectroscopy under various operating conditions has shown a direct correlation between energy efficiency and intensity of CO* emission bands. These results and those obtained with a LiNbO3 plate placed onto the active electrode suggest that high temperature electrons contribute to the splitting of CO2 through an enhancement in the formation of CO2+ intermediate species. Results obtained for CO2 + O-2 mixtures confirm this view and suggest that back recombination processes involving CO and O-2 may reduce the overall splitting efficiency. The study of mixtures of CO2 and dry air has proved the capacity of fermelectric packed-bed reactors to efficiently decompose CO2 with no formation of harmful NxOy subproducts in conditions close to those in real facilities. The found enhancement in energy efficiency with respect to that found for the pure gas decomposition supports that new reaction pathways involving nitrogen molecules are contributing to the dissociation reaction. We conclude that PZT moderated packed-bed plasma reactors is an optimum alternative for the decompositon of CO2 in real gas flows and ambient conditions.

We introduce herein the advanced application of low-pressure plasma procedures for the development of piezo and triboelectric mode I hybrid nanogenerators. Thus, plasma assisted deposition and functionalization methods are presented as key enabling technologies for the nanoscale design of ZnO polycrystalline shells, the formation of conducting metallic cores in core@shell nanowires, and for the solventless surface modification of polymeric coatings and matrixes. We show how the perfluorinated chains grafting of polydimethylsiloxane (PDMS) provides a reliable approach to increase the hydrophobicity and surface charges at the same time that keeping the PDMS mechanical properties. In this way, we produce efficient Ag/ZnO convoluted piezoelectric nanogenerators supported on flexible substrates and embedded in PDMS compatible with a contact-separation triboelectric architecture. Factors like crystalline texture, ZnO thickness, nanowires aspect ratio, and surface chemical modification of the PDMS are explored to optimize the power output of the nanogenerators aimed for harvesting from low-frequency vibrations. Just by manual triggering, the hybrid device can charge a capacitor to switch on an array of color LEDs. Outstandingly, this simple three-layer architecture allows for harvesting vibration energy in a wide bandwidth, thus, we show the performance characteristics for frequencies between 1 Hz and 50 Hz and demonstrate the successful activation of the system up to ca. 800 Hz.

The effect of helium content on the morphology, crystallinity, and composition of aluminum films was investigated by depositing He-loaded Al films onto Si substrates via direct current (DC) magnetron sputtering in different Ar/He plasma mixtures. Three different plasma regimes were identified depending on the percentage of He in the gas phase. For a low He to total gas ratio (ΓHe ≤ 70%), the plasma is dominated by argon, where Ar+ ions contribute to sputter out the target atoms. The films deposited in this regime exhibited the classical dense columnar structure and contain very low amount of He (below 2%). Then, as ΓHe increases, helium ions begin to be formed and more fast He neutrals reach the substrate, affecting the film growth. As He amount increased in the gas phase up to 95%, the proportion of He inserted in the films rised up to ⁓15 at. %. Moreover, bubbles/porosity were formed inside the films; those obtained in pure He plasma presented a highly porous fiberform nanostructure. All results confirmed that the modification of the film characteristics was related to the change of the deposition conditions when Ar was replaced by He and to the insertion/release mechanisms of He during the growth.

Identification of hydrocarbons and crude oils is typically carried out with samples that, taken from natural sources or refineries, must be brought to the laboratory for their analysis with rather sophisticated instruments. Alternatively, "in situ" procedures have been also developed for this purpose. In this work, we propose the use of a series of several sensor systems based on photonic transducers in the form of chips for the identification and classification of crude oils and hydrocarbons through the determination of their refractive index in the visible and absorption in the near infrared regions of the electromagnetic spectrum. Two of the photonic transducers rely on modifications of a Bragg microcavity and they monitor the changes in visible light interference phenomena that occur in response to the variation of the refractive index of oils. The third one, in the form of a dielectric mirror, monitors the near infrared absorption of crude oils and hydrocarbons through the recording of a transflectance spectrum. The capacity of these transducers for crude oil identification is proved by the analysis of a series of oils and distilled fractions that have been properly identified and classified as a function of their density and partition of long hydrocarbon chains. The three photonic transducers are operated with optical fibers and can be used in static and dynamic modes, this latter under conditions that are especially well-suited for "insitu" analysis of oil streams in real facilities. The proved resistance of the chips to high pressure and temperature conditions supports their suitability to withstand harsh working environments as those existing in extraction wells.

Formic acid is an advantageous liquid organic hydrogen carrier. It is relatively nontoxic and can be synthesized by the reaction of CO2 with sustainable hydrogen or by biomass decomposition. As an alternative to more widely studied powdery catalysts, supported Pd-C catalytic thin films with controlled nanostructure and compositions were newly prepared in this work by magnetron sputtering on structured supports and tested for the formic acid decomposition reaction. A two-magnetron configuration (carbon and tailored Pd-C targets) was used to achieve a reduction in Pd consumption and high catalyst surface roughness and dispersion by increasing the carbon content. Activity and durability tests were carried out for the gas phase formic acid decomposition reaction on SiC foam monoliths coated with the Pd-C films and the effects of column width, surface roughness and thermal pre-reduction time were investigated. Activity of 5.04 mol(H2)center dot g(Pd)(-1)center dot h(-1) and 92% selectivity to the dehydrogenation reaction were achieved at 300 degrees C for the catalyst with a lower column width and higher carbon content and surface roughness. It was also found that deactivation occurs when Pd is sintered due to the elimination of carbon and/or the segregation and agglomeration of Pd upon cycling. Magnetron sputtering deposition appears as a promising and scalable route for the one-step preparation of Pd-C catalytic films by overcoming the different deposition characteristics of Pd and C with an appropriate experimental design.

Nanostructured Nb-C thin films were prepared by direct current magnetron sputtering (DC-MS) and high-power impulse magnetron sputtering (HiPIMS). The films were characterized in depth by X-ray diffraction (XRD), grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy, electron probe microanalysis, and Raman spectroscopy. The mechanical properties were measured by nanoindentation, and the tribological properties were measured by pin-on-disk tests in ambient air. The wear tracks and ball scars were analyzed by Raman spectroscopy to elucidate the tribochemical reactions that occurred at the contact area and to determine the wear mechanism for each specimen type. The thermal stability of the coatings was studied up to 1000 degrees C using Raman spectroscopy and XRD. The samples prepared by DC-MS were very dense, and the phase composition changed from purely nanocrystalline (Nb2C and NbC) to a mixture of NbC crystals embedded in an amorphous carbon-based matrix (NbC/a-C(:H)). However, the samples prepared by HiPIMS developed a marked columnar morphology with a NbC/a-C(:H) nanocomposite structure. The hardness values ranged from 11 to 20 GPa depending on the deposition technique and the amount of the soft a-C(:H) phase present in the sample. The tribological properties of all the coatings were remarkably good when the carbon content was approximately 50 at.%. The formation of a lubricating sp(2)-rich C tribofilm between the ball and coating during the pin-on-disk tests was observed by Raman spectroscopy. The tribofilm formed preferentially on the samples prepared by HiPIMS, which had higher C contents. At 750 degrees C, the degradation of the NbC phases resulted in the formation of an additional a-C phase and niobium oxides.

The eventual exploitation of one-dimensional nanomaterials needs the development of scalable, high yield, homogeneous and environmentally friendly methods capable of meeting the requirements for fabrication of functional nanomaterials with properties on demand. In this article, we demonstrate a vacuum and plasma one-reactor approach for the synthesis of fundamental common elements in solar energy and optoelectronics, i.e. the transparent conducting electrode but in the form of nanotube and nanotree architectures. Although the process is generic and can be used for a variety of TCOs and wide-bandgap semiconductors, we focus herein on indium doped tin oxide (ITO) as the most previously researched in previous applications. This protocol combines widely applied deposition techniques such as thermal evaporation for the formation of organic nanowires serving as 1D and 3D soft templates, deposition of polycrystalline layers by magnetron sputtering, and removal of the templates by simply annealing under mild vacuum conditions. The process variables are tuned to control the stoichiometry, morphology, and alignment of the ITO nanotubes and nanotrees. Four-probe characterization reveals the improved lateral connectivity of the ITO nanotrees and applied on individual nanotubes shows resistivities as low as 3.5 +/- 0.9 x 10(-4) omega cm, a value comparable to that of single-crystalline counterparts. The assessment of diffuse reflectance and transmittance in the UV-Vis range confirms the viability of the supported ITO nanotubes as random optical media working as strong scattering layers. Their further ability to form ITO nanotrees opens a path for practical applications as ultra-broadband absorbers in the NIR. The demonstrated low resistivity and optical properties of these ITO nanostructures open a way for their use in LEDs, IR shields, energy harvesting, nanosensors, and photoelectrochemical applications.

In order to explore the potentialities of Cr1-x(Al)xNy materials in multilayer-based solar selective coatings (SSC) for high temperature applications (T > 500 °C), the optical behavior of Cr1-x(Al)xNy films is studied in this work. Two sets of layers (CrNy and Cr1-xAlxNy) were prepared by direct current (DC) and high-power impulse magnetron sputtering (HiPIMS) technology. The deposition parameters: N2 flux, HiPIMS frequency and aluminum sputtering power, were modified to get a wide variety of stoichiometries. The composition, morphology, phases and electronic structure of the films were characterized in depth. The optical behavior was determined by UV–Vis–NIR and FTIR spectroscopies, and the optical constants were obtained from the measured transmittance and reflectance spectra based on appropriate dielectric function models. Our results indicate that small changes in the layer composition influence the optical constants. In particular, a metallic-like behavior was obtained for CrNy layers with N vacancies (CrN0.95 and CrN0.67 films) while a semiconductor-like behavior was observed for CrN1.08. Thus, the CrNy films can be used as effective absorber layer in multilayer-based SSC, and namely, the CrN0.67 film as an IR reflector/absorber layer too. Likewise, the optical properties of Cr1-xAlxNy layers can also be tuned from metallic to semiconductor-like behavior depending on the chemical composition. Indeed, the absorption coefficients of Cr1-xAlxNy films with optimized Al content and N-vacancies are comparable to those reported for state-of-the-art materials such as TiAlN or TiAlCrN. In addition, a Cr0.96Al0.04N0.89 film was found to be a suitable IR reflector/absorber layer.

Applying a modified coprecipitation method, maghemite and anatase nanoparticles embedded in graphene oxide and multiwall carbon nanotube frameworks were prepared, and a detailed structural characterization is presented. Transmission electron images have revealed that the multiwall carbon nanotubes and graphene oxide act as substrates to reduce the nanoparticle agglomeration with narrow sizes of ca. 9-20 nm, in agreement with the results of the Rietveld refinement, which have also indicated their crystallite apparent size and shapes using the spherical harmonics approach. In structural studies of maghemite nanoparticles by Raman spectroscopy, it was found that the effect of optical density and laser power intensity plays a significant role. When no optical filter was located between the powder sample and the laser source, a transformation from the gamma-Fe2O3 to the alpha-Fe2O3 phase was observed, as demonstrated by the disappearance of the characteristic broad Raman peak (A(1g)) of the gamma-Fe2O3 phase when increasing the laser power. X-ray photoelectron spectroscopy has also brought insights into the functionalization mechanism, suggesting that the one-pot reduction of the graphene oxide is favored by the alkaline gamma-Fe2O3 nanoparticle growth. The temperature dependence of the Fe-57 Mossbauer spectra has indicated that the effective anisotropy constant of Fe oxide-based nanoparticles is similar to that of bulk maghemite, and magnetic relaxation of Fe3+ spins depends on particle sizes.

In this work, we have developed a new kind of nanocolumnar birefringent Bragg microcavity (BBM) that, tailored by oblique angle deposition, behaves as a selective transducer of volatile organic compounds (VOCs). Unlike the atomic lattice origin of birefringence in anisotropic single crystals, in the BBM, it stems from an anisotropic self-organization at the nanoscale of the voids and structural elements of the layers. The optical adsorption isotherms recorded upon exposure of these nanostructured systems to water vapor and VOCs have revealed a rich yet unexplored phenomenology linked to their optical activity that provides both capacity for vapor identification and partial pressure determination. This photonic response has been reproduced with a theoretical model accounting for the evolution of the form birefringence of the individual layers upon vapor condensation in nanopores and internanocolumnar voids. BBMs that repel water vapor but are accessible to VOCs have been also developed through grafting of their internal surfaces with perfluorooctyltriethoxysilane molecules. These nanostructured photonic systems are proposed for the development of transducers that, operating under environmental conditions, may respond specifically to VOCs without any influence by the degree of humidity of the medium.

Maximizing the electrochromic response of tungsten oxide-based systems demands highly porous electrode layers that facilitate the incorporation of electrolyte cations during the reduction process. In this work, amorphous and porous WO3 thin films were grown on indium tin dioxide glass substrates by magnetron sputtering at oblique angles at two different plasma gas pressures. Remarkably, the film that showed higher porosity presented a worse electrochromic response in terms of durability, time response and charge density capacity. This result is analyzed and explained on the basis of the features of the porous structure of the films: While the typical nanostructure developed at low pressures possesses large and connected pore voids with few ramifications, the nanostructure generated at a higher pressure presents a rather sponge-like porous structure with numerous and small well-connected voids. A general discussion on the role of the porous structure and, particularly, on the accessible pore volume and area is carried out. It is concluded that not only the accessible pore volume, defining the volume of electrolyte that stays inside the layer, but also the accessible pore area, which defines the efficiency of the incorporation/release of Li+ cations within the electrode material, determine the efficiency and reversibility of the electrochromic response.

Design of bioinspired materials that mimic the extracellular matrix (ECM) at the nanoscale is a challenge in tissue engineering. While nanofibrillar gelatin materials mimic chemical composition and nano-architecture of natural ECM collagen components, it lacks the characteristic D-staggered array (D-periodicity) of 67 nm, which is an important cue in terms of cell recognition and adhesion properties. In this study, a nanofibrous gelatin matrix with improved biomimicry is achieved using a formulation including a minimal content of D-periodic self-assembled atelocollagen. We suggest a processing route approach consisting of the thermally induced phase separation of the gelatin based biopolymeric mixture precursor followed by chemical-free material cross-linking. The matrix nanostructure is characterized using field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), wide angle X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The cell culture assays indicate that incorporation of 2.6 wt.% content of D-periodic atelocollagen to the gelatin material, produces a significant increase of MC3T3-E1 mouse preosteoblast cells attachment and human mesenchymal stem cells (hMSCs) proliferation, in comparison with related bare gelatin matrices. The presented results demonstrate the achievement of an efficient route to produce a cost-effective, compositionally defined and low immunogenic “collagen-like” instructive biomaterial, based on gelatin.

Nanostructuration and 2D patterning of thin films are common strategies to fabricate biomimetic surfaces and components for microfluidic, microelectronic or photonic applications. This work presents the fundamentals of a surface nanotechnology procedure for laterally tailoring the nanostructure and crystalline structure of thin films that are plasma deposited onto acoustically excited piezoelectric substrates. Using magnetron sputtering as plasma technique and TiO2 as case example, it is demonstrated that the deposited films depict a sub-millimetre 2D pattern that, characterized by large lateral differences in nanostructure, density (up to 50%), thickness, and physical properties between porous and dense zones, reproduces the wave features distribution of the generated acoustic waves (AW). Simulation modelling of the AW propagation and deposition experiments carried out without plasma and under alternative experimental conditions reveal that patterning is not driven by the collision of ad-species with mechanically excited lattice atoms of the substrate, but emerges from their interaction with plasma sheath ions locally accelerated by the AW-induced electrical polarization field developed at the substrate surface and growing film. The possibilities of the AW activation as a general approach for the tailored control of nanostructure, pattern size, and properties of thin films are demonstrated through the systematic variation of deposition conditions and the adjustment of AW operating parameters.

Snake skins evolved to withstand permanent friction and wear during sliding. Here, the microstructure of ventral scales of the snake Lampropeltis getula californiae was analyzed using scanning electron microscopy, and the long-term dynamic friction behavior was investigated by reciprocating sliding friction tests. A smooth epoxy resin with similar elasticity modulus and hardness was used for comparison purposes. Strong differences in frictional and wear mechanisms between the two materials were revealed in spite of similar mechanical properties. Snake skin showed a considerably lower frictional coefficient that kept stable over several thousands of sliding cycles. A reduction of the stick-slip behavior was also denoted by analyzing the variation of the friction coefficient in the forward and reverse motion influencing the wear mechanism. This frictional behavior can be explained by three different but complementary mechanisms: fibrous layered composite material of the skin with a gradient of material properties, surface microstructure, and the presence of ordered layers of lipid molecules at the skin surface.

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.

Infusion of low surface tension liquids in nanostructured surfaces is currently used to promote an anti icing response, although the long term stability of these systems is often jeopardized by losses of the infused liquid. In this work, we propose an alternative to the infusion procedure to induce a more effective and long lasting anti-icing capacity. The method consists of a combination of surface nanostructuration with the chemical grafting of fluorocarbon molecules. Al6061 substrates have been subjected to laser roughening and further modified with a nanostructured Al2O3 thin film to achieve a dual roughness and porous surface state. These surfaces have been subjected to a grafting treatment with perfluorooctyltriethoxysilane (PFOTES) vapor or, for comparative purposes, infused with a low surface tension liquid. A comparative analysis of the wetting, water condensation and anti-icing properties of these two systems showed an outstandingly better performance for the grafted surfaces with respect to the infused ones. Grafted surfaces were markedly superhydrophobic and required higher water vapor pressures to induce condensation. When looking for their anti-icing capacity, they presented quite long freezing delay times for supercooled water droplets (i.e. almost four hours) and exhibited a notably low ice accretion in a wind tunnel test. The high aging resistance and durability of these grafted surfaces and the reproducibility of the results obtained when subjected to successive ice accretion cycles show that molecular grafting is an efficient anti-icing methodology that, in aggressive media, may outperform the classical infusion procedures. The role of the fluorocarbon chains anchored on the surface in inducing an anti-icing functionality is discussed.

We devise a unique heteronanostructure array to overcome a persistent issue of simultaneously utilizing the surface-enhanced Raman scattering, inexpensive, Earth-abundant materials, large surface areas, and multifunctionality to demonstrate near single-molecule detection. Room-temperature plasma-enhanced chemical vapor deposition and thermal evaporation provide high-density arrays of vertical TiO2 nanotubes decorated with Ag nanoparticles. The role of the TiO2 nanotubes is 3-fold: (i) providing a high surface area for the homogeneous distribution of supported Ag nanoparticles, (ii) increasing the water contact angle to achieve superhydrophobic limits, and (iii) enhancing the Raman signal by synergizing the localized electromagnetic field enhancement (Ag plasmons) and charge transfer chemical enhancement mechanisms (amorphous TiO2) and by increasing the light scattering because of the formation of vertically aligned nanoarchitectures. As a result, we reach a Raman enhancement factor of up to 9.4 × 107, satisfying the key practical device requirements. The enhancement mechanism is optimized through the interplay of the optimum microstructure, nanotube/shell thickness, Ag nanoparticles size distribution, and density. Vertically aligned amorphous TiO2 nanotubes decorated with Ag nanoparticles with a mean diameter of 10–12 nm provide enough sensitivity for near-instant concentration analysis with an ultralow few-molecule detection limit of 10–12 M (Rh6G in water) and the possibility to scale up device fabrication.

Sodium borohydride constitutes a safe alternative for the storage of hydrogen with a high gravimetric content. Catalytic hydrolysis of sodium borohydride permits on-demand hydrogen generation for multiple applications. In this field, the rational design of efficient metal catalysts deposited on structured supports is highly desirable. For most reactions, chemical methods are the most commonly used methods for the preparation of supported metal catalysts. Physical vapour deposition techniques are emerging as an alternative for the preparation of catalytic materials because of their multiple advantages. They permit the one-step deposition of catalysts on structured supports with controlled microstructure and composition, avoiding the multi-step procedures and the generation of hazardous by-products associated with chemical routes.

In this short review, we will describe the available literature on the application of physical vapour deposition techniques for the preparation of supported metal catalysts for the hydrolysis of sodium borohydride. The effects of the deposition parameters on the properties of the catalytic materials will be discussed, and strategies for further improvement will be proposed. Here, we also present our new results on the study of nanoporous Pt catalysts that are prepared through the chemical dealloying of magnetron sputtered Pt-Cu thin films for the hydrolysis of sodium borohydride. We discuss the capabilities of the technique to tune the microstructure from columnar to closed porous microstructures, which, coupled with dealloying, produces more active supported catalysts with lower noble metal loading. At the end, we briefly mention the application of PVD for the preparation of supported catalysts for the hydrolysis of ammonia borane, another hydrogen generating reaction of high interest nowadays.

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.

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. 

Herein we have developed nanostructured nickel-based electrode films for anion exchange membrane water electrolysis (AEMWE). The electrodes were prepared by magnetron sputtering (MS) in an oblique angle configuration and under various conditions aimed at preparing metallic, oxide, or oxyhydroxide films. Their electrochemical analysis has been complemented with a thorough physicochemical characterization to determine the effect of microstructure, chemical state, bilayer structure, and film thickness on the oxygen evolution reaction (OER). The maximum electrocatalytic activity was found for the metallic electrode, where analysis by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) demonstrated that the active catalytic phase at the surface after its electrochemical conditioning is a kind of oxidized nickel oxide/hydroxide layer with the thickness of a few nanometers. Electrochemical impedance spectroscopy analysis of these steady-state working electrodes supports that the enhanced performance of the metallic nickel anode vs other chemical states resides in the easier electron transfer through the electrode films and the various interlayers built up during their fabrication and activation. The long-term steady-state operation of the anodes and their efficiency for water splitting was proved in a full-cell AEMWE setup incorporating magnetron-sputtered metallic nickel as the cathode. This work proves that MS is a suitable technique to prepare active, stable, and low-cost electrodes for AEMWE and the capacity of this technique to control the chemical state of the electrocatalytically active layers involved in the OER.

Optical properties of polycrystalline molybdenum are determined from ultraviolet up to extreme ultraviolet by reflection electron energy loss spectroscopy (REELS). Calculations are performed within the dielectric response theory by means of the quantitative analysis of electron energy losses at surfaces QUEELS-epsilon (k, omega)-REELS software [Surf. Interface Anal. 36, 824 (2004)] that allows the simulation of inelastic scattering cross sections, using a parametric energy loss function describing the optical response of the material. From this energy loss function, the real and imaginary parts of the dielectric function, the refractive index, and the extinction coefficient are deduced and compared with previously published results.

The properties of ZnO based materials for ethanol detection have been studied. Cu doped samples obtained from different precursors have been investigated. ZnO and ZnS have been used as host and Cu and CuO as dopant sources.

The sensing measurements have been mostly performed at room temperature. To monitor the effect of the presence of gas, resistivity and photoluminescence experiments with and without sensing gas have been carried out. The sensing behaviour is affected by the nature of the precursors used. For ZnO:Cu and ZnO:CuO series, a higher sensitivity is obtained at the lower gas concentrations, the better response is obtained for the sample ZnO:Cu with wt.1% of metallic copper. Strong segregation effects observed in these samples could be deleterious for the sensing properties. In the series ZnS:CuO, no segregation is observed, however the sensing behaviour is erratic and attributed to the reduction of Cu ions to the metallic state.

The aim of our study is to evaluate different implant surface treatments using TiIV and TiV in in vitro and in vivo studies. An in vitro study was established comprising four study groups with treated and untreated TiIV titanium discs (TiIVT and TiIVNT) and treated and untreated TiV titanium discs (TiVT and TiVNT). The surface treatment consisted in a grit blasting treatment with alumina and double acid passivation to modify surface roughness. The surface chemical composition and the surface microstructure of the samples were analyzed. The titanium discs were subjected to cell cultures to determine cell adhesion and proliferation of osteoblasts on them. The in vivo study was carried out on the tibia of three New Zealand rabbits in which 18 implants divided into three experimental groups were placed (TiIVT, TiIVNT, and TiVT). Micro-computed tomography (micro-CT) was performed to determine bone density around the implants. The results showed that cell culture had minor adhesion and cell proliferation in TiIVT and TiVT within the first 6 and 24 h. However, no differences were found after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study; however, there was a positive trend in bone formation in the groups with a treated surface. Conclusions: All groups showed a similar response to in vitro cell proliferation cultures after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study

The nano-porosity embedded into the tilted and separated nanocolumns characteristic of the microstructure of evaporated thin films at oblique angles has been critically assessed by various variants of the positron annihilation spectroscopy. This technique represents a powerful tool for the analysis of porosity, defects and internal interfaces of materials, and has been applied to different as-deposited SiO2 and TiO2 thin films as well as SiO2/TiO2 multilayers prepared by electron beam evaporation at 70 and 85 zenithal angles. It is shown that, under same deposition conditions, the concentration of internal nano-pores in SiO2 is higher than in TiO2 nanocolumns, while the situation is closer to this latter in TiO2/SiO2 multilayers. These features have been compared with the predictions of a Monte Carlo simulation of the film growth and explained by considering the influence of the chemical composition on the growth mechanism and, ultimately, on the structure of the films.

N-Heterocyclic Thiones (NHT) proved to be efficient ligands for the stabilization of small platinum nanoparticles (1.3-1.7 nm), synthesized by decomposition of [Pt(dba)(2)], under a H-2 atmosphere, in the presence of variable sub-stoichiometric amounts of the NHT. Full characterization by means of TEM, HR-TEM, NMR, ICP, TGA and XPS have been carried out, providing information about the nature of the metal nanoparticles and the interaction of the NHT ligands to the metal surface. Importantly, DFT calculations indicate that some NHT ligands interact with the metal through the C & xe001;C double bond of the imidazole fragment in addition to the sulfur atom, thus providing additional stabilization to the nanoparticles. According to XPS, TGA and ICP techniques, the surface coverage by the ligand increases by decreasing the size of the substituents on the nitrogen atom. The platinum nanoparticles have been used as catalyst in the hydroboration of alkynes. The most active system is that with a less covered surface area lacking an interaction of the ligand by means of the C & xe001;C double bond. This catalyst hydroborates alkynes with excellent selectivities towards the monoborylated anti-Markovnikov product (vinyl-boronate) when one equiv. of borane is used. Very interestingly, aliphatic alkynes undergo a second hydroborylation process leading to the corresponding 1,1- and 1,2-diboroylated species with good selectivities towards the former.

Cr-doped diamond-like carbon (Cr-DLC) films with Cr contents ranging from 3 up to 20 at. % were synthesised in a codeposition process with HiPIMS (Cr deposition) and DC-pulsed technology (C deposition). The application of HiPIMS at low frequencies was observed to significantly enhance the energy density during the Cr plasma discharge due to the interaction of Cr-C species. The higher energy bombardment at low HiPIMS frequencies allowed doping with Cr the DLC structure avoiding the graphitization of the carbon structure. EELS spectroscopy was used to evaluate sp(3) content and Raman was used for sp(2) structural characterization of the films. Enhanced mechanical properties (hardness up to 30 GPa) were observed with nanoindentation for Cr-doped DLC at low frequencies. High temperature nanoindentation tests were also performed from room temperature to 425 degrees C in order to evaluate the evolution of hardness and Young Modulus with temperature. The results showed that the mechanical properties at high temperature mainly depend on the initial sp(3)-sp(2) structure. Tribological tests were carried out in air from room temperature to 250 degrees C. Cr-doped DLC coatings deposited by low-frequency HiPIMS showed lower friction and wear compared to undoped DLC.

In this work, we show that multilayer graphene forms by methanol decomposition at 280 degrees C on an electrochemically promoted nickel catalyst film supported on a K-beta Al2O3 solid electrolyte. In operando near ambient pressure photoemission spectroscopy and electrochemical measurements have shown that polarizing negatively the Ni electrode induces the electrochemical reduction and migration of potassium to the nickel surface. This elemental potassium promotes the catalytic decomposition of methanol into graphene and also stabilizes the graphene formed via diffusion and direct K-C interaction. Experiments reveal that adsorbed methoxy radicals are intermediate species in this process and that, once formed, multilayer graphene remains stable after electrochemical oxidation and back migration of potassium to the solid electrolyte upon positive polarization. The reversible diffusion of ca. 100 equivalent monolayers of potassium through the carbon layers and the unprecedented low-temperature formation of graphene and other carbon forms are mechanistic pathways of high potential impact for applications where mild synthesis and operation conditions are required.

The photocatalytic properties of SnO2 nanocrystals are tuned by varying their morphology and microstructure. SnO2 nanoparticles and nanowedges have been synthesized using hydrothermal methods, while microwave irradiation techniques have given nanospheres. Detailed structural and chemical characterization of these different morphologies has been accomplished. The influence of SnO2 morphology on photocatalytic activity has been examined by monitoring the degradation of aqueous methylene blue dye. Results demonstrate that changing the morphology of the SnO2 modulates both surface area and levels of surface defects and that these alterations are reflected in the photocatalytic properties of the materials. The degradation of methylene blue dye (98%) in the presence of SnO2 nanoparticles under simulated solar irradiation is superior to previously reported photocatalyst performance and is comparable to that of standard TiO2 (Degussa P-25). The SnO2 nanoparticles perform better than both the nanowedges and nanospheres and this is attributed to the number of surface defects available to the high surface area material. They also reveal outstanding recyclability and stability. 

We experimentally analyze different growth regimes of Ti thin films associated to the existence of kinetic energy-induced relaxation mechanisms in the material's network when operating at oblique geometries. For this purpose, we have deposited different films by evaporation and magnetron sputtering under similar geometrical arrangements and at low temperatures. With the help of a well-established growth model we have found three different growth regimes: (i) low energy deposition, exemplified by the evaporation technique, carried out by species with typical energies in the thermal range, where the morphology and density of the film can be explained by solely considering surface shadowing processes, (ii) magnetron sputtering under weak plasma conditions, where the film growth is mediated by surface shadowing mechanisms and kinetic-energy-induced relaxation processes, and (iii) magnetron sputtering under intense plasma conditions, where the film growth is highly influenced by the plasma, and whose morphology is defined by nanocolumns with similar tilt than evaporated films, but with much higher density. The existence of these three regimes explains the variety of morphologies of nanocolumnar Ti thin films grown at oblique angles under similar conditions in the literature.

WO3 thin film electrodes were successfully prepared by magnetron sputtering (MS) deposition under an oblique angle configuration (OAD). Intercalation of Na ions in the tungsten oxide layers has been studied using electrochemical techniques. Sample characterization before and after sodium intercalation has been carried out by Raman, XPS and XRD measurements. ToF-SIMS analysis has been also performed in order to analyze the element depth profiles along the electrode thickness. Electron microscopy evaluation of the cross section confirms the porous structure of the coatings. Batteries integrating these WO3 electrodes have a discharge capacity of 120 mA h g(-1) at the initial cycles and show an adequate capacity retention upon 300 cycles. The WO3-OAD thin-films are proposed as promising electrodes for Na-ion batteries.

Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to similar to 15 cm(2)) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (DePuy Synthes) and a pseudo-rectangular bone plate extracted from a patient were coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments were performed: Analysis of bacterial adhesion and biofilm formation, and osteoblasts-bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings.

The aim of this study was to characterize the hydration performance and the bioactive response of the new bioactive endodontic cement MTA HP repair (HP), comparing its physicochemical parameters with those of ProRoot MTA White (Pro) and NeoMTA Plus (Neo). Un-hydrated precursor materials were characterized by X-ray fluorescence, laser diffraction, N2 physisorption and field emission gun scanning electron microscopy (FEG-SEM). Setting time was assessed according to ASTM specification C 266. Hydrated materials were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and (FEG-SEM). Bioactivity evaluation in vitro was carried out, by soaking processed cement disk in simulated body fluid (SBF) during 168 h. The cements surface was studied by FT-IR, FEG-SEM, and energy dispersive X-ray. Release to the SBF media of ionic degradation products was monitored using inductively coupled plasma atomic emission spectroscopy. HP showed shorter initial setting time compared to Pro and Neo and produce a quick and effective bioactive response in vitro in terms of phosphate phase surface coating formation. This higher bioactive response for HP is correlated with increasing calcium aluminate content, increasing surface area of un-hydrated powder precursor and the increasing release capacity of Si ionic products of the final hydrated product. The higher bioactive response of MTA HP repair highlights this material, as very interesting to further investigate its performance to improve the outcome of vital pulp therapy procedures. 

Background: To characterize the chemical composition and textural parameters of the MTA Repair HP precursor powder and their influence to hydration performance. Material and Methods: Un-hydrated precursor material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), laser diffraction (LD), N2 physisorption and field emission gun scanning electron microscopy (FEG-SEM). Setting time was assessed according to ASTM specification C 266. Hydrated material was analysed by XRD, FT-IR, energy dispersive X-ray (EDX) analysis and FEG-SEM. Results: Ca3SiO5 and Ca2SiO4, in addition to CaWO4 as radiopacifier are the main compositional phases. Other measured parameters indicate high specific surface area of 4.8 m2 g-1, high aluminium content of 1.7 wt.% and low initial and final setting times of 12 and 199 min, respectively. Singular microstructural features consisting of high aspect ratio nanoparticles are main constituents of un-hydrated precursor. Besides, FEM-SEM observation shows notably growth of hexagonal shaped plate-like morphologies homogeneously distributed along the sample during hydration process. Conclusions: The short setting time measured for HP Repair, is correlated with high surface area of precursor powder, high Al content and the absence of compositional sulphate phases. 

This work reports a phenomenological comparative study of atmospheric pressure barrier plasmas using ferroelectric (ferroelectric barrier discharge (FBD)) and dielectric (dielectric barrier discharge (DBD)) plates to moderate the discharge. For FBD operation and large inter-electrode distances, experiments with helium carried out in a parallel plate reactor as a function of applied voltage have shown an enhancement of one order of magnitude in the charge transferred through the circuit. In a similar way to DBDs, FBDs rendered a laterally localized arrangement of discrete columnar discharges with a pattern distribution and an overall current intensity that depended on operation conditions. However, unlike the regular columnar pattern found for DBD operation, discharge columns in the FBD mode appear randomly and inhomogeneously distributed on the ferroelectric surface. This geometrical behavior of FBD plasma columns, as well as the singular variation of current with applied voltage and the particular shape characteristics of the current discharge curves have been accounted for by the high capacity of ferroelectric surfaces to randomly accumulate charge and to promote the emission of secondary electrons in the presence of a plasma.

Unlike topography patterning, widely used for numerous applications and produced by means of different technologies, there are no simple procedures to achieve surface compositional patterning at nanometric scales. In this work we have developed a simple method for 2D patterning the composition of thin films. The method relies on the magnetron sputtering deposition at oblique angles onto patterned substrates made by laser induced periodic surface structures (LIPSS). The method feasibility has been demonstrated by depositing SiOx thin films onto LIPSS structures generated in Cr layers. A heterogeneous and aligned distribution of O/Si ratios (and different Sin+ chemical states) along the LIPSS structure in length scales of some hundreds nm's has been proven by angle resolved X-ray photoelectron spectroscopy and a patterned arrangement of composition monitored by atomic force microscopy-Raman analysis. The obtained results are explained by the predictions of a Monte Carlo simulation of this deposition process and open the way for the tailored one-step fabrication of surface devices with patterned compositions.

Novel antibacterial materials for implants and medical instruments are essential to develop practical strategies to stop the spread of healthcare associated infections. This study presents the synthesis of multifunctional antibacterial nanocoatings on polydimethylsiloxane (PDMS) by remote plasma assisted deposition of sublimated chlorhexidine powders at low pressure and room temperature. The obtained materials present effective antibacterial activity against Escherichia coli K12, either by contact killing and antibacterial adhesion or by biocide agents release depending on the synthetic parameters. In addition, these multifunctional coatings allow the endure hydrophilization of the hydrophobic PDMS surface, thereby improving their biocompatibility. Importantly, cell-viability tests conducted on these materials also prove their non-cytotoxicity, opening a way for the integration of this type of functional plasma films in biomedical devices.

LaAl1-xNixO3 (with x = 0.05 and 0.2) perovskite oxides were successfully synthesized and its behavior under reduction atmosphere was studied. HRTEM and STEM studies, coupled to HAADF and EDX detection, allowed to evidence the Ni exsolution process to the surface of the solid and to build nano-catalytic centers. The size of these centers is independent of the reduction conditions in the range studied. The high specific surface of the raw material, its porosity and the structure defects could be responsible of the low temperature at which the exsolution process starts. The content of Ni dopants allows the control of Ni centers size on the surface and the synthesis method provides Ni-nanoparticles strongly anchored to the resultant support.

The thin film configuration presents obvious practical advantages over the 1D implementation in energy harvesting systems such as easily manufacturing and processing, and long-lasting and stable devices. However, ZnO-based piezoelectric nanogenerators (PENGs) generally rely on the exploitation of single-crystalline nanowires because of their self-orientation in the c-axis direction and ability to accommodate long deformations resulting in high piezoelectric performance. Herein, we show an innovative approach to produce PENGs by combining polycrystalline ZnO layers fabricated at room temperature by plasma-assisted deposition with supported small-molecule organic nanowires (ONWs) acting as 1D scaffolds. Such hybrid nanostructures present convoluted core-shell morphology, formed by a single-crystalline organic nanowire conformally surrounded by a poly-crystalline ZnO shell and combine the organic core mechanical properties with the ZnO layer piezoelectric response. In a step forward towards the integration of multiple functions within a single wire, we have also developed ONW-Au-ZnO nanoarchitectures including a gold shell acting as inner electrode achieving output piezo-voltages up to 170 mV. The synergistic combination of functionalities in the ONW-Au-ZnO devices promotes an enhanced performance generating piezo-currents one order of magnitude larger than the ONW-ZnO nanowires and superior to the thin film nanogenerators for equivalent and higher thicknesses.

CuxCo3-xO4 ultra-thin films, deposited by magnetron sputtering at oblique angles have been used as anodic catalysts in anion exchange membrane water electrolysers. It has been demonstrated that the used deposition procedure provides porous and amorphous samples with a strict control of the total catalyst load and Co/Cu ratio. Electrocatalytic tests showed a maximum performance for the oxygen evolution reaction at Co/Cu atomic ratio around 1.8. The optimized anodic catalyst presented a long-term stability confirmed by accelerated lifetime tests together with the chemical surface analysis of the used samples. The effect of the crystallization of a single layer CuxCo3-xO4 and a multilayer (CuO/Co3O4)(n) anodic catalyst samples was also investigated. The observed loss of catalytic performance found in both cases may prove that a particular local chemical environment around the Co and Cu sites acts as an efficient catalytic site for the oxygen evolution reaction. A catalyst film with the optimum Co/Cu atomic ratio was incorporated into a Membrane Electrode Assembly, using a sputtered Ni film as cathode. Current density values up to 100 mA cm(-2) at 2.0 V were obtained in 1.0 M KOH electrolyte. Upon normalization by the amount of catalyst, this performance is one of the highest reported in literature.

In the present study, two kinds of metal oxide/carbon nanocomposite were prepared through calcination of MIL-101(Fe, Cr). The morphological and structural properties of the specimens were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer, Emmett, and Teller analysis, energy dispersive Xray spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The electrode materials were also electrochemically investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques in 6 M KOH electrolyte. Because of synergistic effect of metal oxides and carbon, the obtained samples showed excellent performance; in a way that Cr2O3/C and Fe Oy/C showed high specific capacitance of 420 F g(-1) and 114 F g(-1) at current density of 2 A g(-1), respectively. The Cr2O3/C electrode also displayed high rate capability even at scan rate of 1500 mV s(-1). Moreover, we successfully developed an asymmetric supercapacitor in which Cr2O3/C served as positive electrode and Fe Oy/C served as negative electrode. The asymmetric device can deliver an energy density of 9.6 W h kg(-1) and power density of 8000 W kg(-1), with 93% capacitance retention after 3000 charge-discharge cycles. These outcomes show that the MOF-derived metal oxide/carbon composite can be regarded as a promising development for advanced electrode materials for applying in supercapacitors.

The potential human health risks following the exposure to inorganic nanoparticles (NPs) is a very important issue for their application in leather finishing industry. The aim of our study was to investigate the cytotoxic effect of silver (Ag)/titanium dioxide (TiO2) NPs on human cells. Photocatalytic NPs were prepared by electrochemical deposition of Ag on the surface of TiO2 and nitrogen (N)-TiO2 NPs and, subsequently, physicochemical characterized. Then, a set of experiments have been performed to study the cytotoxicity and cell death mechanisms involved, the changes in cell morphology and the production of ROS induced in human keratinocytes (HaCaT) and human lung epithelial cells (A549) by exposure to NPs. Moreover, the changes in major signaling pathways and the inflammatory response induced by Ag/N-TiO2 NPs in A549 cells were investigated. The data showed that cell death by late apoptosis/necrosis is induced in cells as function of the dose and the type of NPs and is characterized by morphological changes and cytoskeletal disorganization and an increase in reactive oxygen species (ROS) production. The exposure of A549 cells to Ag/N-TiO2 NPs determine the activation of ERK1/2 MAP-kinase pathway and the release of pro-inflammatory mediators CXCL1, GM-CSF and MIF, known to be involved in the recruitment of circulating neutrophils and monocytes.

In this study, electrochemical energy storage performances of an efficient Ni-Fe sulfide and hydroxide supported on porous nickel foam are compared. X-ray diffraction (XRD), X-rayphotoelectron spectroscopy (XPS) and energy-dispersive X-ray spectrometer (EDS) results confirmed the formation of Ni-Fe-S and Ni-Fe-OH electrodes. In addition, Brunauer-Emmett Teller (BET) was used to determine the specific surface area of the prepared materials. Moreover, the morphologies were observed by scanning electron microscopy (SEM). The brilliant characteristics of Ni-Fe-S could be attributed to transport acceleration in electrolyte ions and electrons, occurrence of redox reactions as well as the higher conductivity of the sample. From stand point of comparison, the capacitance of Ni-Fe-S is more than that of Ni-Fe-OH. Therefore, the exchange of O2- with S2- in Ni-Fe-OH lattice obviously improves the electrochemical performance. The as-fabricated Ni-Fe sulfide electrode exhibits a tremendous specific capacitance of 884.9Fg(-1) at 1A g(-1). Furthermore, an assembled asymmetric supercapacitor device using the activated carbon as negative electrode and this smart configuration (Ni-Fe-S) as positive electrode also provided a maximum specific power and specific energy of 8000Wkg(-1), 37.9 Whkg(-1), respectively. Also, it shows cycling stability with 88.8% capacitance retention after 1700 cycles in aqueous electrolyte, demonstrating its potential application in the next-generation high-performance supercapacitors used for energy storage.

This work aims at presenting an innovative method for tailoring the morphology of functionalized plasma polymer films (PPF). The approach is based on the formation of a plasma polymer bilayer system in which the two layers differ by their chemical composition and cross-linking degree. As a case study, propanethiol-based plasma polymer films have been investigated. As revealed by a much higher S/C ratio than in the propanethiol precursor (i.e. 0.83 vs 0.33), it has been demonstrated that the bottom layer contains a large fraction of trapped sulfur-based molecules (e.g. H2S). When further covered by a denser PPF formed at higher energetic conditions, a three-dimensional morphological reorganization takes place giving rise to the micro/nano structuration of the organic material. The shape, the dimensions as well as the density of the generated structures are found to depend on the thickness of both coatings involved in the bilayer structure, offering a great flexibility for surface engineering. Annealing experiments unambiguously confirm the major role played by the sulfur-based trapped molecules for inducing the reshaping process. The whole set of data clearly paves the way for the development of an innovative approach for finely tailoring the morphology of functionalized PPF at the micro/nano scale.

The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi-equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.

Lead halide perovskite nanocrystals have demonstrated their potential as active materials for optoelectronic applications over the past few years. Nevertheless, one issue that hampers their applicability has to do with the observation of photoluminescence intermittency, commonly referred to as "blinking", as in their inorganic counterparts. Such behavior, reported for structures well above the quantum confinement regime, has been discussed to be strongly related to the presence of charge carrier traps. In this work, we analyze the characteristics of this intermittency and explore the dependence on the surrounding atmosphere, showing evidence for the critical role played by the presence of oxygen. We discuss a possible mechanism in which a constant creation/annihilation of halide-related carrier traps takes place under light irradiation, with the dominant rate being determined by the atmosphere.

Herein, the preparation of 1D TiO2 nanocolumnar films grown by plasma-enhanced chemical vapor deposition is reported as the electron selective layer (ESL) for perovskite solar devices. The impact of the ESL architecture (1D and 3D morphologies) and the nanocrystalline phase (anatase and amorphous) is analyzed. For anatase structures, similar power conversion efficiencies are achieved using an ESL either the 1D nanocolumns or the classical 3D nanoparticle film. However, lower power conversion efficiencies and different optoelectronic properties are found for perovskite devices based on amorphous 1D films. The use of amorphous TiO2 as electron selective contact produces a bump in the reverse scan of the current-voltage curve as well as an additional electronic signal, detected by impedance spectroscopy measurements. The dependence of this additional signal on the optical excitation wavelength used in the IS experiments suggests that it stems from an interfacial process. Calculations using a drift-diffusion model which explicitly considers the selective contacts reproduces qualitatively the main features observed experimentally. These results demonstrate that for a solar cell in which the contact is working properly the open-circuit photovoltage is mainly determined by bulk recombination, whereas the introduction of a "bad contact" shifts the balance to surface recombination.

Nanolayered CrAIN and CrAIYN/CrAIN (average contents of Al approximate to 25 at.% and Y approximate to 1.6 at. %) coatings are deposited on M2 and 316 steel substrates and heated to 1000 degrees C in air for 2 h to study their oxidation mechanism, the thermal stability and the reactive element (RE) effect of yttrium. CrAIN on M2 develops a Cr2O3/Al2O3 passivation layer that preserves in high degree the fcc-CrAIN structure however iron ions leave the substrate and travel to the surface along the column boundaries. The CrAIYN/CrAIN coatings deposited on steels are not stable at 1000 degrees C, and the initial fcc-CrAIN phase is partially transformed to hcp-Al(O)N and Cr-Fe phases (M2) and Cr2N and Al2O3 (316). The addition of Y changes the predominant scale growth direction. Inward oxygen diffusion becomes dominant but a reduction of the oxide scale thickness as compared to CrAIN is not observed. The advanced microstructural analysis made by transmission electron microscopy combined with electron energy loss spectroscopy determined that yttrium migrates mainly to the oxide scale (forming mixed oxides with substrate elements - V and Mo, either as dispersed particles or segregated at the grain boundaries) in M2, and to the oxide interface and column boundaries (forming Al-Y oxides and YN, respectively) in 316 steel. The benefits of addition of Y in improving the oxidation resistance are discussed comparatively with literature data. The RE effect of yttrium is thus observed to be dependent on the substrate, film architecture and composition.

This work reports about the sensing and biosensing applications of a novel screen printed electrode (SPE) modified by nanostructured nickel oxide thin films obtained by reactive magnetron sputtering under an oblique angle configuration. Using these films as electrodes we demonstrate their ability to detect hydrogen peroxide under neutral pH conditions. Furthermore, as a proof-of-concept, NiO-modified SPEs have been developed and their cholesterol biosensing properties determined by cyclic voltammetry and chronoamperometry.

Herein we present a combined study of the evolution of both the photoluminescence (PL) and the surface chemical structure of organic metal halide perovskites as the environmental oxygen pressure rises from ultrahigh vacuum up to a few thousandths of an atmosphere. Analyzing the changes occurring at the semiconductor surface upon photoexcitation under a controlled oxygen atmosphere in an X-ray photoelectron spectroscopy (XPS) chamber, we can rationalize the rich variety of photophysical phenomena observed and provide a plausible explanation for light-induced ion migration, one of the most conspicuous and debated concomitant effects detected during photoexcitation. We find direct evidence of the formation of a superficial layer of negatively charged oxygen species capable of repelling the halide anions away from the surface and toward the bulk. The reported PL transient dynamics, the partial recovery of the initial state when photoexcitation stops, and the eventual degradation after intense exposure times can thus be rationalized.

In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min(-1).g(CoRu)(-1) at 25 degrees C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pinon-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 x 10(-6) mm(3)/N m to 0.15 and 2 x 10(-7) mm(3)/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process. 

This work presents results in the field of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fired Ceramics has been used, as a non-crystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these fields of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using different buffer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes.

(1) Background: The use of physical barriers to prevent the invasion of gingival and connective tissue cells into bone cavities during the healing process is called guided bone regeneration. The objective of this in-vitro study was to compare the growth of human osteoblasts on Poly(Lactic-co-Glycolic) (PLGA) membranes modified with oxygen plasma and Hydroxyapatite (HA), silicon dioxide (SiO2), and titanium dioxide (TiO2) composite nanoparticles, respectively. (2) Methods: All the membranes received a common treatment with oxygen plasma and were subsequently treated with HA nanostructured coatings (n = 10), SiO2 (n = 10) and TiO2 (n = 10), respectively and a PLGA control membrane (n = 10). The assays were performed using the human osteoblast line MG-63 acquired from the Center for Scientific Instrumentation (CIC) from the University of Granada. The cell adhesion and the viability of the osteoblasts were analyzed by means of light-field microphotographs of each condition with the inverted microscope Axio Observer A1 (Carl Zeiss). For the determination of the mitochondrial energy balance, the MitoProbe (TM) JC-1 Assay Kit was employed. For the determination of cell growth and the morphology of adherent osteoblasts, two techniques were employed: staining with phalloidin-TRITC and staining with DAPI. (3) Results: The modified membranes that show osteoblasts with a morphology more similar to the control osteoblasts follow the order: PLGA/PO2/HA > PLGA/PO2/SiO2 > PLGA/PO2/TiO2 > PLGA (p < 0.05). When analysing the cell viability, a higher percentage of viable cells bound to the membranes was observed as follows: PLGA/PO2/SiO2 > PLGA/PO2/HA > PLGA/PO2/TiO2 > PLGA (p < 0.05), with a better energy balance of the cells adhered to the membranes PLGA/PO2/HA and PLGA/PO2/SiO2. (4) Conclusion: The membrane in which osteoblasts show characteristics more similar to the control osteoblasts is the PLGA/PO2/HA, followed by the PLGA/PO2/SiO2.

In this work we present a new concept for energy sensitive radiation-beam scintillator detectors based on a luminescent multilayer design, where each layer within the stack consists of a rare-earth-doped highly transparent oxide. For a given type of particle beam (i.e., protons, a particles, etc.), its penetration depth, and therefore its energy loss at a particular buried layer, depends on its initial kinetic energy. Relying on this principle and since the intensity of the luminescent response of each layer and substrate should be proportional to the energy deposited by the radiation beam, we prove that a characteristic energy dependent color emission is obtained depending on both the phosphors integrated in the luminescent stack and on the primary energy and type of particle beam. Phosphor doping, emission efficiency, layer thickness, and multilayer structure design are key parameters to achieve a broad gamut in colorimetric response. The developed scintillators are designed to operate in a transmission geometry (light detection from the opposite side of the incident radiation) which is well suited for high energy particle detection in fields such as oncotherapy, space radiation, or of fusion studies. The principles of the method are illustrated with a case example typical of ion beam accelerators devoted to materials analysis. It is obtained that the kinetic energy of protons/alpha particle beams can be distinguished and evaluated with a sensitivity of 0.06/0.25 chromaticity units per MeV in the 0.7-2.0 MeV range. 

This work presents a simple experimental procedure to probe light confinement effects in photonic structures. Two types of porous 1D Bragg microcavities with two resonant peaks in the reflection gap were prepared by physical vapor deposition at oblique angle configurations and then infiltrated with dye solutions of increasing concentrations. The unusual position shift and intensity drop of the transmitted resonant peak observed when it was scanned through the dye absorption band have been accounted for by the effect of the light trapped at their optical defect layer. An experimentally observed giant absorption of the dye molecules and a strong anomalous dispersion in the refractive index of the solution are claimed as the reasons for the observed variations in the Bragg microcavity resonant feature. Determining the giant absorption of infiltrated dye solutions is proposed as a general and simple methodology to experimentally assess light trapping effects in porous photonic structures.

In this work we report the use of polarization active porous 1D Bragg microcavities (BM) prepared by physical vapor deposition at oblique angles for the optofluidic analysis of liquid solutions. These photonic structures consist of a series of stacked highly porous layers of two materials with different refractive indices and high birefringence. Their operational principle implies filling the pores with the analyzed liquid while monitoring with linearly polarized light the associated changes in optical response as a function of the solution refractive index. The response of both polarization active and inactive BMs as optofluidic sensors for the determination of glucose concentration in water solutions has been systematically compared. Different methods of detection, including monitoring the BM wave retarder behavior, are critically compared for both low and high glucose concentrations. Data are taken in transmission and reflection modes and different options explored to prove the incorporation of these nanostructured transducers into microfluidic systems and/or onto the tip of an optical fiber. This analysis has proven the advantages of the polarization active transducer sensors for the optofluidic analysis of liquids and their robustness even in the presence of light source instabilities or misalignments of the optical system used for detection.

In this work we investigate by in-situ near-ambient pressure photoemission (NAPP) spectroscopy the phenomenon of Electrochemical Promotion of Catalysis (EPOC). We studied the reduction and diffusion kinetics of alkaline ions in a solid electrolyte cell formed by a nickel electrode supported on K+-beta-alumina electrolyte. Experiments in ultra-high vacuum and in the presence of steam showed that the amount of potassium atoms supplied to the surface is probably affected by nickel electronic modifications induced by adsorbed OH- groups. It was also deduced that part of the segregated potassium would be adsorbed at inner interfaces where it would be inaccessible to the photoelectron analyzer. A migration mechanism of the promoter is proposed consisting in: (i) the electrochemical reduction of the alkali ions (potassium) at the Ni/solid electrolyte/gas interface; (ii) the spillover of potassium atoms onto the Ni gas-exposed surface; and (iii) the diffusion of potassium atoms to Ni inner grain boundary interfaces.

A fluidic permeable and stable in wet media, MBG-NfGel, device consisting of a mesoporous ceramic embodied in a nanofibrillar biodegradable polymer has been processed using appropriate thermally induced phase separation (TIPS) processing variables of 5.4% (wt/v) gelatin in 50/50 water/ethanol (v/v) ratio. The device comprises high surface area mesoporous bioactive glass (MBG) microparticles within a fibrous matrix of 170 nm average diameter nanofibers gelatin, forming a meshwork of 0.2-1.6 mu m range voids. Gentamicin sulphate (GS) antibiotic high loading capacity and sustained release ability, as well as in vitro bioactivity and osteoprogenitor cells biocompatibility supports long-term antibacterial and bone growth stimulation properties. Antibiotic local delivery functionality in vitro of this device has been analysed and discussed in relation to other systems previously reported. The presented device properties as well as its industrial scalability potential, in terms of process reliability and absence of toxic chemical agents, low raw material biopolymer cost and immunogenicity, are other important advantages. These advantages rank MBG-NfGel device as a potential candidate to further development for application as local antibiotic device in bone surgery and therapy.

0D nanocomposites formed by small nanoparticles embedded in a second phase are very interesting systems which may show properties that are beyond those observed in the original constituents alone. One of the main parameters to understand the behavior of such nanocomposites is the determination of the separation between two adjacent nanoparticles, in other words, the thickness of the embedding phase. However, its experimental measurement is extremely complicated. Therefore, its evaluation is performed by an indirect approach using geometrical models. The ones typically used represent the nanoparticles by cubes or spheres. 
In this paper the used geometrical models are revised, and additional geometrical models based in other parallelohedra (hexagonal prism, rhombic and elongated dodecahedron and truncated octahedron) are presented. Additionally, a hybrid model that shows a transition between the spherical and tessellated models is proposed. Finally, the different approaches are tested on a set of titanium carbide/amorphous carbon (TiC/a-C) nanocomposite films to estimate the thickness of the a-C phase and explain the observed hardness properties. 

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering.

Organohalide perovskites have emerged as highly promising replacements for thin-film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous-functionalized imidazolium cation during the preparation of a highly stable cesium-based mixed perovskite material Cs-0.05(MA(0.15)FA(0.85))(0.95)Pb(I0.85Br0.15)(3) (MA= methylammonium; FA= formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous-functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (> 100 days) along with power conversion efficiencies exceeding 16%. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability.

Thermal therapy using laser sources can be used in combination with other cancer therapies to eliminate tumors. However, high precision temperature control is required to avoid damage in healthy surrounding tissues. Therefore, in order to detect laser induced temperature changes, we have used the fluorescence signal of the enhanced Green Fluorescent Protein (eGFP) over-expressed in an E. coli bacterial culture. For that purpose, the bacteria expressing eGFP are injected in a Fabry-Perot (FP) optofluidic planar microcavity. In order to locally heat the bacterial culture, external infrared or ultraviolet lasers were used. Shifts in the wavelengths of the resonant FP modes are used to determine the temperature increase as a function of the heating laser pump power. Laser induced local temperature increments up to 6-7 degrees C were measured. These results show a relatively easy way to measure laser induced local temperature changes using a FP microcavity and using eGFP as a molecular probe instead of external nanoparticles, which could damage/alter the cell. Therefore, we believe that this approach can be of interest for the study of thermal effects in laser induced thermal therapies. 

The novelty of this study is the addition of an ultrathin layer of nanostructured hydroxyapatite (HA) on oxygen plasmamodified poly(lactic-co-glycolic) (PLGA) membranes (PO2) in order to evaluate the efficiency of this novel material in bone regeneration. Methods: Two groups of regenerative membranes were prepared: PLGA (control) and PLGA/PO2/HA (experimental). These membranes were subjected to cell cultures and then used to cover bone defects prepared on the skulls of eight experimental rabbits. Results: Cell morphology and adhesion of the osteoblasts to the membranes showed that the osteoblasts bound to PLGA were smaller and with a lower number of adhered cells than the osteoblasts bound to the PLGA/PO2/HA membrane (p < 0.05). The PLGA/PO2/HA membrane had a higher percentage of viable cells bound than the control membrane (p < 0.05). Both micro-CT and histological evaluation confirmed that PLGA/PO2/HA membranes enhance bone regeneration. A statistically significant difference in the percentage of osteoid area in relation to the total area between both groups was found. Conclusions: The incorporation of nanometric layers of nanostructured HA into PLGA membranes modified with PO2 might be considered for the regeneration of bone defects. PLGA/PO2/HA membranes promote higher osteosynthetic activity, new bone formation, and mineralisation than the PLGA control group.

Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3 - 2.0 keV. This technique allows the evaluation of the optical response in these ultraviolet spectral regions of a thin layer of material, and the analysis is straightforward. It is performed within the dielectric response theory by means of the QUEELS-epsilon(k,omega)-REELS software developed by Tougaard and Yubero [Surf. Interface Anal. 36, 824 ( 2004)]. The method consists basically in the fitting of experimentally determined single-scattering electron energy loss cross sections with a parametric energy loss function of the corresponding material, to the one calculated within a dielectric response formalism. The obtained refractive index and extinction coefficients, as well as the identified electronic transitions are compared, when available, with previously published results. 

Plasma treatment is recognized as a suitable technology to improve germination efficiency of numerous seeds. In this work Quinoa seeds have been subjected to air plasma treatments both at atmospheric and low pressure and improvements found in germination rate and percentage of success. Seed water uptake by exposure to water vapor, although slightly greater for plasma treated seeds, did not justify the observed germination improvement. To identify other possible factors contributing to germination, the chemical changes experienced by outer parts of the seed upon plasma exposure have been investigated by X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM-EDX). XPS revealed that the outer layers of the Quinoa plasma treated seeds were highly oxidized and appeared enriched in potassium ions and adsorbed nitrate species. Simultaneously, SEM-EDX showed that the enrichment in potassium and other mineral elements extended to the seed pericarp and closer zones. The disappearance from the surface of both potassium ions and nitrate species upon exposure of the plasma treated seeds to water vapor is proposed as a factor favoring germination. The use of XPS to study chemical changes at seed surfaces induced by plasma treatments is deemed very important to unravel the mechanisms contributing to germination improvement.

This article establishes the bases for a vacuum and plasma supported methodology for the fabrication at mild temperatures of nanostructured platinum in the form of porous layers and nanocolumns using platinum octaethylporphyrin as precursor. In addition, the application of these materials as tunable optical filters and nano-counterelectrodes is proved. On one hand, the transparency in the ultraviolet-visible-near infrared range can be adjusted precisely between 70% and 1% by tuning the deposition and processing conditions, obtaining a high spectral planarity. Deviations of the spectra from an ideal flat filter are below 4%, paving the way to the fabrication of neutral density filters. The transparency limit values yield a sheet resistivity of approximate to 1350 and 120 Omega square(-1), respectively. On the other hand, the catalytic properties of the nanostructures are further demonstrated by their implementation as counterelectrodes of excitonic solar cells surpassing the performance of commercial platinum as counterelectrode in a 20% of the overall cell efficiency due to simultaneous enhancement of short-circuit photocurrent and open-circuit photovoltage. One of the most interesting features of the developed methodology is its straightforward application to other metal porphyrins and phthalocyanines readily sublimable under mild vacuum and temperature conditions.

The development of scaffolds mimicking native bone tissue composition and structure is a challenge in bone tissue engineering. 3D scaffolds with both an interconnected macropore structure and nanotextured surfaces are required. However, 3D scaffolds processed by microfabrication usually lack of nanotextured surface, while nanotextured materials generated by bottom-up nanofabrication are difficult to process conforming scaffolds having well interconnected microsized cavities. In this work, the processing of reticulated (macropore interconnected) structures using nanostructured precursors has been performed to improve the mechanical properties of the scaffolds. The application of a fibrillar collagen coating, using less than 1 wt% collagen per scaffold, has allow a significant increase of the compressive strength while preserving a high surface area and nanopore accessibility. Besides, the fibrillar nanostructured collagen coating promotes hydroxyapatite mineralization. Two different collagen-coating procedures are applied showing interesting differences in terms of mechanical performance.

Moisture-induced degradation in perovskite solar cells was thoroughly investigated by structural (SEM, EDS, XRD and XPS) and device characterization (impedance and intensity modulated photocurrent spectroscopy) techniques. Both the influence of the perovskite composition and the nature of the hole selective material were analyzed. The degradation rate was found to be significantly slower for mixed perovskites and P3HT-based devices. However, for a fixed degradation degree (defined as a 50% drop from the initial photocurrent), all configurations show similar features in small-perturbation analysis. Thus, a new mid-frequency signal appears in the impedance response, which seems to be related to charge accumulation at the interfaces. In addition, faster recombination, with a more important surface contribution, and slower transport were clearly inferred from our results. Both features can be associated with the deterioration of the contacts and the formation of a higher number of grain boundaries.

Plasma reactions offer an attractive alternative route for the synthesis of a variety of valuable chemical compounds. Here we investigate the parameters that determine the efficiency of ammonia synthesis in a ferroelectric packed bed dielectric barrier discharge (DBD) reactor. The effects of varying the operating frequency, the size of the ferroelectric pellets and the inter-electrode distance have been systematically studied. Under optimised conditions nitrogen conversions in excess of 7% were achieved, higher than those previously obtained using DBD reactors. These findings are discussed with respect to variations in the electrical characteristics of the reactor under operating conditions and in the light of emission spectra obtained as a function of reactant flow rates. These encouraging results signpost future developments that could very substantially improve the efficiency of ammonia synthesis by means of DBD technology.

The essential role of oxygen in enabling heterogeneously catalyzed Glaser–Hay coupling of phenylacetylene on Ag(100) was elucidated by STM, laboratory and synchrotron photoemission, and DFT calculations. In the absence of coadsorbed oxygen, phenylacetylene formed well-ordered dense overlayers which, with increasing temperature, desorbed without reaction. In striking contrast, even at 120 K, the presence of oxygen led to immediate and complete disruption of the organic layer due to abstraction of acetylenic hydrogen with formation of a disordered mixed layer containing immobile adsorbed phenylacetylide. At higher temperatures phenylacetylide underwent Glaser–Hay coupling to form highly ordered domains of diphenyldiacetylene that eventually desorbed without decomposition, leaving the bare metal surface. DFT calculations showed that, while acetylenic H abstraction was otherwise an endothermic process, oxygen adatoms triggered a reaction-initiating exothermic pathway leading to OH(a) + phenylacetylide, consistent with the experimental observations. Moreover, it was found that, with a solution of phenylacetylene in nonane and in the presence of O2, Ag particles catalyzed Glaser–Hay coupling with high selectivity. Rigorous exclusion of oxygen from the reactor strongly suppressed the catalytic reaction. Interestingly, too much oxygen lowers the selectivity toward diphenyldiacetylene. Thus, vacuum studies and theoretical calculations revealed the key role of oxygen in the reaction mechanism, subsequently borne out by catalytic studies with Ag particles that confirmed the presence of oxygen as a necessary and sufficient condition for the coupling reaction to occur. The direct relevance of model studies to a mechanistic understanding of coupling reactions under conditions of practical catalysis was reaffirmed.

A multilayer luminescent design concept is presented to develop energy sensitive radiation-beam monitors on the basis of colorimetric analysis. Each luminescent layer within the stack consists of rare-earth-doped transparent oxides of optical quality and a characteristic luminescent emission under excitation with electron or ion beams. For a given type of particle beam (electron, protons, alpha particles, etc.), its penetration depth and therefore its energy loss at a particular buried layer within the multilayer stack depend on the energy of the initial beam. The intensity of the luminescent response of each layer is proportional to the energy deposited by the radiation beam within the layer, so characteristic color emission will be achieved if different phosphors are considered in the layers of the luminescent stack. Phosphor doping, emission efficiency, layer thickness, and multilayer structure design are key parameters relevant to achieving a broad colorimetric response. Two case examples are designed and fabricated to illustrate the capabilities of these new types of detector to evaluate the kinetic energy of either electron beams of a few kilo-electron volts or a particles of alpha few mega-electron volts.

The aging of supported Ag nanostructures upon storage in ambient conditions (air and room temperature) for 20 months has been studied. The samples are produced on glass substrates by pulsed laser deposition (PLD); first a 15 nm thick buffer layer of amorphous aluminum oxide (a-Al2O3) is deposited, followed by PLD of Ag. The amount of deposited Ag ranges from that leading to a discontinuous layer up to an almost-percolated layer with a thickness of <6 nm. Some regions of the as-grown silver layers are converted, by laser induced dewetting, into round isolated nanoparticles (NPs) with diameters of up to ~25 nm. The plasmonic, structural and chemical properties of both as-grown and laser exposed regions upon aging have been followed using extinction spectroscopy, scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. The results show that the discontinuous as-grown regions are optically and chemically unstable and that the metal becomes oxidized faster, the smaller the amount of Ag. The corrosion leads to the formation of nitrile species due to the reaction between NO x species from the atmosphere adsorbed at the surface of Ag, and hydrocarbons adsorbed in defects at the surface of the a-Al2O3 layer during the deposition of the Ag nanostructures by PLD that migrate to the surface of the metal with time. The nitrile formation thus results in the main oxidation mechanism and inhibits almost completely the formation of sulphate/sulphide. Finally, the optical changes upon aging offer an easy-to-use tool for following the aging process. They are dominated by an enhanced absorption in the UV side of the spectrum and a blue-shift of the surface plasmon resonance that are, respectively, related to the formation of a dielectric overlayer on the Ag nanostructure and changes in the dimensions/features of the nanostructures, both due to the oxidation process.

We study the effect of wall slip on the measured values of the yield stress of magnetorheological (MR) fluids. For this aim we used a rheometer provided with parallel-plate geometries of two types, distinguished by having smooth or rough surfaces. We found that wall slip led to the underestimation of the yield stress when measuring geometries with smooth surfaces were used, and that this underestimation was more pronounced for the static than for the dynamic yield stress. Furthermore, we analysed the effect that both irreversible particle aggregation due to colloidal interactions and reversible magnetic fieldinduced particle aggregation had on the underestimation provoked by wall slip. We found that the higher the degree of aggregation the stronger the underestimation of the yield stress. At low intensity of the applied magnetic field irreversible particle aggregation was dominant and, thus, the underestimation of the yield stress was almost negligible for well-dispersed MR fluids, whereas it was rather pronounced for MR fluids suffering from irreversible aggregation. As the magnetic field was increased the underestimation of the yield stress became significant even for the best dispersed MR fluid.