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International audience; The p-type Ge-doped (0, 1, 4 and 7 at.%) Mg

In this paper, ZnO-ZnS composite structure is proposed as a new efficient and earth-abundant absorber material for thin-film solar cells (TFSCs). Promising elaboration strategy based on combining vacuum thermal evaporation technique and oxidation process under an annealing temperature of 500 °C was used to prepare ZnO-ZnS composite with high sun-light absorption capabilities. The fabricated microstructure was then characterized by Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and UV–Visible absorption spectroscopy. The influence of the annealing time on the structural and optical performances of the prepared samples was investigated. Surface analysis demonstrated the ZnO decoration of ZnS thin-film, where SEM images showed dense and pinhole-free ZnO-ZnS composite with micrometer-sized grains and a few voids visible at thin-films surface. Optical characterization showed that the prepared thin-film absorber exhibits an optical band-gap of 2.65 eV with a high Total Absorption Efficiency (TAE) of 62% and an absorption coefficient exceeding 2 × 104 cm−1. In addition, I-V characteristics under dark and 1-sun illumination of the microstructured ZnO-ZnS composite were extracted. It was revealed that the proposed absorber showcases a high visible photoresponse. Therefore, promoting effective light-scattering effects, this innovative ZnO-ZnS composite offers a sound pathway to prepare alternative low-cost absorbers for the future development of TFSCs.

Light polarization control is a key factor in modern photonics. Recent advances in surface plasmon manipulation have introduced the prospect of more compact and more efficient devices for this purpose. However, the current plasmonic-based polarization optics remain much larger than the wavelength of light, which limits the design degrees of freedom. Here, we present a plasmonic traveling-wave nanoantenna using a gold-coated helical carbon nanowire end-fired with a dipolar aperture nanoantenna. Our nonresonant helical nanoantenna enables tunable polarization control by swirling surface plasmons on the subwavelength scale and taking advantage of the optical spin–orbit interaction. Four closely packed helical traveling-wave nanoantennas (HTNs) are demonstrated to locally convert an incoming light beam into four beams of tunable polarizations and intensities, with the ability to impart different polarization states to the output beams in a controllable way. Moreover, by near-field coupling four HTNs of opposite handedness, we demonstrate a subwavelength waveplate-like structure providing a degree of freedom in polarization control that is unachievable with ordinary polarization optics and current metamaterials., Nano-optics: polarization control Gold-coated carbon nanowire spirals offer an ultra-compact means of controlling the polarization state of light. The helical structures, designed and fabricated by a French-Chinese collaboration from the FEMTO-ST Institute in France and Jinan University in China, use surface plasmons and optical spin-orbit interactions to convert an incoming linearly-polarized light beam into a circularly polarized output. Incident light is coupled into a plasmon mode of the helical nanowires via a rectangular aperture nanoantenna that perforates a thin gold layer at the base of the helix. The small size of the nanowires means that several can be packed together and the team demonstrate an array of 4 coupled structures, two with a left-handed helix and two with a right-handed helix, allowing tunable polarization control. Potential applications include use in displays, data storage, microscopy and sensing.

International audience; The prebiotic organization of chemicals into compartmentalized ensembles is an essential step to understand the transition from inert molecules to living matter. Compartmentalization is indeed a central property of living systems. Fatty acids represent the simplest prebiotic amphiphiles capable of self-assembling into membrane-bound vesicles, and have therefore emerged as valuable molecules to create models of protocellular compartments. Here, the main experimental findings that support this idea are reviewed, together with approaches to increase the stability of fatty acid vesicles in adverse pH, salt or temperature conditions. Recent studies on the self-assembly of fatty acids into membrane-free coacervate micro-droplets are then discussed, providing a promising new paradigm for prebiotic compartmentalization. We last argue that the unique possibility of cycling between fatty acid vesicles and coacervates paves the way to an exciting new hypothesis for the emergence of the first living protocells.

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International audience; Delafossite CuFeO2 films have been synthesized by reactive magnetron sputtering at different substrate temperatures from 380 up to 550 °C. The films adopt the rhombohedral structure from 380 to 550 °C. At the highest temperature, the delafossite phase partially dissociates in FCC Cu and Fe3O4 magnetite phases. In addition to the average crystallite size increase, a change of the preferential orientation in the out-of-plane direction from the [012] to [006] directions occurs between 460 and 510 °C. Modelling of the optical properties shows the presence of 2 interband transitions in the visible range. The 1st main transition at 1.5 eV is ascribed to the absorption component parallel to the c-axis whereas the 2nd transition (2.10 – 2.26 eV) is related to the absorption component in the (a, b) plane. Both evolutions with temperature of the refractive index (~ 2.5) and absorption coefficient (~ 10-3 cm-1) in the infrared suggest the formation of secondary phases. The electronic conductivity, dominated by positive charge carrier, varied from 0.01 to 10 S m-1 according to the preferential orientation and to the presence of secondary phases. A very small amount of a short-range ferromagnetic component (magnetization ~ 10 kA m-1 at 1.5 T) is clearly observed at room temperature thanks to magnetometry confirming the formation of secondary phases undetected by X-ray diffraction. In addition to depend on the film orientation, the presence of secondary phases in weak proportion alters the optical and electrical behaviours such as the transmittance in the visible range..

Metallic platinum&ndash, titanium coatings were deposited by co-sputtering of two metallic Pt and Ti targets in pure argon atmosphere. The titanium concentrations varied from 0 to 47 atomic percent and were adjusted as a function of the current applied to the titanium target. The structural and chemical features of these films were assessed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). All as-deposited coatings exhibit a perfect covering of the alumina pellets&rsquo, substrate surface. The coatings containing more than 4 at.% Ti are amorphous, whereas the others crystallize in the face-centered cubic (fcc) structure of platinum. After an annealing treatment under air for 2 h, all of the coatings adopt the fcc structure with a crystallization temperature depending on the titanium content. For titanium concentrations higher than 32 at.%, the TiO2 phase appears during the annealing treatment. For the smaller film thickness of Pt&ndash, Ti alloys (15 nm), the Ostwald ripening mechanism is observed by SEM increasing the annealing temperature regardless of the content of Ti. The film resistivity measured at room temperature is lower than 7 10&minus, 4 &Omega, &middot, cm and increases with the temperature to achieve an insulating behavior (in air and reducing atmosphere Ar-H2 (90-10) at 1123 K the resistivity is &rho, 10+36 &Omega, cm). When the thickness of intermetallic Pt3Ti layer is higher than 50 nm, the coating is continuous and the resistivity is below 5 10&minus, cm in air and in reducing atmosphere (Ar with 10% of H2) up to 1273 K.

International audience; Poly(3,4-ethylenedioxythiophene)–polystyrene sulfonate (PEDOT:PSS) conjugated polymer blend and a cationic poly(3-hexylthiophene) (P3HT)-based conjugated polyelectrolyte incorporating imidazolium ionic side groups were first adsorbed as monolayer on inorganic colloidal particles. At the plateau of adsorption isotherm, adsorbed amount of PEDOT:PSS on alumina particles appears lower than the adsorbed amount of P3HT on silica particles. Both polyelectrolytes strongly modify the surface charge of particles as reveals by zeta potential variation. Functionalized particles were then assembled using Layer-by-Layer method in order to prepare (PDDA/Al2O3-PEDOT:PSS)n and (SiO2-P3HT/PEDOT:PSS)n conductive multilayer film. Thicker PDDA/Al2O3-PEDOT:PSS films were elaborated when a drying step was added during the LbL build-up. The same effect was observed when composite particle concentration was increased from 1 to 10 g.L−1. Electrical behavior of film was completely modified in comparison with PDDA/PEDOT:PSS assembly. After heating at 150 °C, no conductivity was detected due to microcracks visible on SEM images. For SiO2-P3HT/PEDOT:PSS assembly, thickness is higher than for PDDA/Al2O3-PEDOT:PSS assembly using the same experimental procedure. However, even if two conductive polyelectrolytes were embedded into the film, conductivity was too low at 30 °C to be measured by van der Pauw technique probably due to the cracking of the film induced by incorporation of silica particles.

International audience; In this paper, novel self-powered, solar-blind UV photodetector (PD) designs based on a ZnO thin-film with engineered back metal layer (BML) were fabricated by RF magnetron sputtering and e-beam evaporation techniques. An exhaustive study concerning the impact of dissimilar BML (Au and Ni) on the device structural, optical and electrical properties was carried out. The measured I–V curves illustrated an asymmetrical behavior, enabling a clear and distinctive photovoltaic mode. Superb sensitivity of 107, high ION/IOFF ratio of 149dB, ultralow dark-noise current less than 11pA and responsivity exceeding 0.27A/W were reached for the prepared ZnO-based UV-PDs in self-powered mode. The role of the engineered BML in promoting effective separation and transfer of the photo-induced carriers was discussed using the band-diagram theory. The influence of the annealing process on the UV-sensor performance was also investigated. The annealed device at 500°C demonstrated a lower dark current of a few picoamperes and a high rejection ratio of 2.2:103, emphasizing its exciting visible blindness characteristics. Therefore, the use of an engineered BML with optimized annealing conditions open up new perspectives to realizing high-performance, self-powered solar-blind UV-PDs based on simple thin film-ZnO structure strongly desirable for various optoelectronic applications.

Plasmonic Au nanoparticles (AuNPs) embedded into a TiO2 dielectric matrix were analyzed by combining two-dimensional and three-dimensional electron microscopy techniques. The preparation method was reactive magnetron sputtering, followed by thermal annealing treatments at 400 and 600 degrees C. The goal was to assess the nanostructural characteristics and correlate them with the optical properties of the AuNPs, particularly the localized surface plasmon resonance (LSPR) behavior. High-angle annular dark field scanning transmission electron microscopy results showed the presence of small-sized AuNPs (quantum size regime) in the as-deposited Au-TiO2 film, resulting in a negligible LSPR response. The in-vacuum thermal annealing at 400 degrees C induced the formation of intermediate-sized nanoparticles (NPs), in the range of 10-40 nm, which led to the appearance of a well-defined LSPR band, positioned at 636 nm. Electron tomography revealed that most of the NPs are small-sized and are embedded into the TiO2 matrix, whereas the larger NPs are located at the surface. Annealing at 600 degrees C promotes a bimodal size distribution with intermediate-sized NPs embedded in the matrix and big sized NPs, up to 100 nm, appearing at the surface. The latter are responsible for a broadening and a redshift, to 645 nm, in the LSPR band because of increase of scattering-to-absorption ratio. Beyond differentiating and quantifying the surface and embedded NPs, electron tomography also provided the identification of "hot-spots". The presence of NPs at the surface, individual or in dimers, permits adsorption sites for LSPR sensing and for surface-enhanced spectroscopies, such as surface enhanced Raman scattering., The authors thank the METSA network (FR3507 CNRS) for the financial support for this work, the Clym consortium for granting access to the Jeol 2010F and TITAN 80-300 keV ETEM. S.K. thanks the French Ministry of Higher Education and Research for the financial support during his PhD which was also supported by the LABEX iMUST (ANR-10-LABX-0064) of Universite de Lyon, within the program "Investissements d'Avenir" (ANR-11-IDEX-0007) operated by the French National Research Agency (ANR). This research was partly supported by the 3Dclean ANR-15-CE09-0009 project granted by the ANR. This research was also sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and FCT Project 9471-RIDTI, co-funded by FEDER and with reference PTDC/FIS-NAN/1154/2014. J.B. acknowledges FCT for his Postdoc Grant (SFRH/BPD/117010/2016) and M.S.R. acknowledges FCT for his PhD Grant (SFRH/BD/118684/2016)., info:eu-repo/semantics/publishedVersion

Conductive polyelectrolyte multilayer films composed of conductive anionic poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and insulating cationic polydiallyldimethylammonium chloride (PDDA) were successfully prepared by layer-by-layer method. The (PDDA/PEDOT:PSS)n multilayer thickness is affected by the PDDA concentration ranging from 0.25 g.L−1 to 1 g.L−1 as well as the number of deposited bilayers and the type of salts used as electrolyte (BaCl2 or NaCl). More precisely, film thickness measured by profilometry increases with PDDA concentration, number of adsorbed bilayers and with the presence of Ba2+ cations. From UV–Visible absorbance spectroscopy, we showed that the amount of adsorbed PEDOT:PSS is greater when PDDA concentration increases and that PEDOT is still incorporated into the multilayer film especially when divalent ions are employed to improve the film growth. Water contact angles were measured on (PDDA/PEDOT:PSS)n films with PEDOT:PSS as the outerlayer. Films are more hydrophobic in the presence of Ba2+ which is probably due to a modification of the PEDOT:PSS core/shell structure. A percolation threshold leading to electrical conduction was determined as a function of the number of adsorbed bilayers. The effect of several parameters such as PDDA concentration, type of salt and temperature on conductivity and activation energy was investigated.

Fabrication of compartmentalised chemical systems with nested architectures and biomimetic properties has important implications for controlling the positional assembly of functional components, spatiotemporal regulation of enzyme cascades and modelling of proto-organelle behaviour in synthetic protocells. Here, we describe the spontaneous capture of glucose oxidase-containing proteinosomes in pH-sensitive fatty acid micelle coacervate droplets as a facile route to multi-compartmentalised host–guest protocells capable of antagonistic chemical and structural coupling. The nested system functions co-operatively at low-substrate turnover, while high levels of glucose give rise to pH-induced disassembly of the droplets, release of the incarcerated proteinosomes and self-reconfiguration into spatially organised enzymatically active vesicle-in-proteinosome protocells. Co-encapsulation of antagonistic enzymes within the proteinosomes produces a sequence of self-induced capture and host–guest reconfiguration. Taken together, our results highlight opportunities for the fabrication of self-reconfigurable host–guest protocells and provide a step towards the development of protocell populations exhibiting both synergistic and antagonistic modes of interaction., Multi-compartmentalised soft micro-systems are used as models of synthetic protocells. Here, the authors developed nested host–guest protocell constructs capable of self-reconfiguration in response to changes in pH generated by antagonistic modes of enzyme-mediated coupling.

Tungsten oxide thin films are grown by DC reactive magnetron sputtering combining glancing angle deposition (GLAD) and reactive gas pulsing process (RGPP). Inclined, zigzag and spiral columnar architectures are produced with various oxygen injections during the growth. The dodecane and ozone sensing properties of these tungsten oxide nanostructured active layers are comparatively studied with that of films deposited by conventional sputtering process. Microstructure, morphologies and electrical behaviors are characterized as a function of the growing conditions. As-deposited films systematically exhibit an amorphous crystal structure with a porous microstructure, which depends on the GLAD architecture. Annealing at 300 °C in air for 12 h leads to a polycrystalline structure keeping voided networks. Dodecane and ozone sensing performances are the most significant for inclined columnar architectures but they also depend on the RGPP sputtering conditions. As a result, the GLAD + RGPP combination proves to be a relevant strategy for the fabricating tungsten oxide nanostructured films as active layers with an attractive potential for gas sensors.

International audience; Tungsten oxide thin films were prepared by DC magnetron sputtering. The reactive gas pulsing processwas implemented to modify tungsten and oxygen concentrations in the films. A rectangular pulsingsignal was used with a pulsing period fixed at P ¼ 16 s, whereas the duty cycle a was systematicallychanged from a ¼ 0e100% of P. The chemical composition of the films showed a gradual increase ofoxygen-to-tungsten concentrations ratio from 0 to more than 3.0 as a function of the duty cycle. Filmsbecame poorly crystallized and even amorphous with an increase of the oxygen content. Similarly, atypical columnar structure was observed for pure or oxygen-rich tungsten films, which vanished whenthe duty cycle was higher than a few % of P. The optical transmittance in the visible range of WOx filmsdeposited on glass also showed a progressive change from absorbent to transparent as the duty cycle wasincreased. Electronic transport properties including conductivity, carrier mobility and concentration alsodemonstrated the controlled and regular evolution of the electrical properties from metallic to insulatorwhen the duty cycle and thus oxygen concentration in the films changed from pure tungsten to overstoichiometricWO3 compound.

Supercritical water (SCW) is widely known to be a powerful gasifying agent, but the supercritical gasification of linear paraffins is a method whose ability to produce H2 has not been studied significantly. Herein, an analysis of the gasification of dodecane, a representative diesel compound, with steam and SCW and the ability of the method to produce H2 under different pressures is reported. In this study, the broadest pressure (1–500 bar) and temperature (550–800 °C) ranges ever studied in this field are covered. We found that a fraction of the short-chain hydrocarbons generated in the thermal cracking of dodecane are turned into polycyclic aromatic compounds and phenol, compounds that hinder gasification. These reactions become more significant as steam at atmospheric pressure is progressively compressed up to SCW at 500 bar; consequently, steam gasification is faster than supercritical gasification. A gasification mechanism that gathers all of the possible pathways is proposed. Despite the slow gasification kinetics in SCW, a pressure slightly above the critical point (250 bar) is the most efficient to produce H2. At this pressure, the long reaction times related to the high SCW density allow a significant amount of CH4 and CO to be reformed into H2; however, further compression is not recommended because gasification is significantly slowed down and H2 production decreases.

Electrical resistivity of tilted columnar thin films is theoretically and experimentally investigated considering the anisotropic structure of the columns. To this end, W and W Cu thin films were deposited by the GLAD co-sputtering technique. These films were prepared using two different sputtering pressures: 2.5 × 10−3 and 15 × 10−3 mbar. Their morphological and crystallographic properties were studied in order to understand the correlations between some structural characteristics and electrical behaviors of these structured films. The influence of the sputtering pressure on the film's morphology was demonstrated and related to the electronic transport properties in these columnar films. For W Cu films, the copper was chemically etched in order to tune even more the electrical properties. By rotating the sample along its azimuthal axis, it was shown that the measured resistivity in the axis perpendicular to the particle flux is maximum, but decreases significantly along the axis parallel to the flux, leading to an anisotropic resistivity coefficient higher than 1.9 for some films. Similarly, an analytical model based-on effective medium approximations was successfully applied to determine the evolution of electrical resistivity versus azimuthal axis for W, W Cu and etched W Cu thin films.

We report on a successful attempt to introduce Al 2 O 3 and AlN nanoparticles in the matrix of a C/C composite via (i) aqueous synthesis of AlOOH nanoparticles in a predensified C/C composite preform, (ii) ceramization of AlOOH into either Al 2 O 3 or AlN, and (iii) final pyrocarbon densification. We show that we were able to synthesize a uniform and thin layer of high aspect ratio (nanoneedle) AlOOH particles at the surface of pyrocarbon coated fibers. This morphology was conserved upon transformation to alumina, however, coalescence into larger compact grains (thus discontinuous) was observed after nitridation. Nevertheless, the ceramic introduction did not alter the microstructure of the resulting composite after full densification. While most of the ceramic/carbon interfaces showed a parallel arrangement of graphene layers at the surface of the ceramic particles, characteristic of weak bonding, a carbon/AlN interface showed a perpendicular arrangement, suggesting strong covalent bonding.

In this work, the advantages provided by supercritical water (SCW) to one of the most extended methods to produce H 2 , the gasification of carbonaceous materials, are investigated. The broad range of experimental conditions assayed (1–1000 bar) allows not only the comparison of the use of steam and SCW but also the investigation of how H 2 production varies within the supercritical region. The results obtained reveal important advantages when the supercritical fluid is used. In the gasification with SCW, H 2 production is greater, and in general, the consumption of the raw material is optimized since more H 2 is obtained when the same amount of solid is consumed. Furthermore, the gaseous streams are very rich in H 2 and CO 2 and poor in CO and CH 4 . On the other hand, the use of two carbonized materials of different natures (a phenolic textile fiber and holm oak wood) allows us to highlight that H 2 production depends strongly on the surface irregularities and surface chemistry of the solid. The material of vegetal origin is more suitable because more H 2 is produced and mixtures of gases that are more easily purified are obtained from it. However, higher amounts of CO 2 than those registered for the solid of synthetic origin are released during its gasification.

UMR BFP - Equipe Mollicutes; International audience; We report on the formation of surfactant-based complex catanionic coacervate droplets in mixtures of decanoic acid and cetylpyridinium chloride or cetyltrimethylammonium bromide. We show that coacervation occurs over a broad range of composition, pH, and ionic strength. The catanionic coacervates consist of elongated micelles, sequester a wide range of solutes including water-soluble organic dyes, polysaccharides, proteins, enzymes, and DNA, and can be structurally stabilized by sodium alginate or gelatin-based hydrogelation. These results suggest that catanionic coacervates could be exploited as a novel surfactant-based membrane- free protocell model.

For green sustainable chemistry, it is crucial to investigate the destruction of such a common pollutant as phenol. This study reports the gasification of phenol with steam and supercritical water (SCW) and shows that gasification under high-pressure SCW is a method that destroys and efficiently converts phenol into valuable products. To the best of our knowledge, the widest pressure range ever investigated in this field is utilized, i.e., from atmospheric pressure steam to SCW at 1000 bar. The high temperature used (700 °C) leads to fast degradation of phenol under all the conditions studied but the amount of phenol gasified does strongly depend on pressure. During gasification, polymeric compounds such as naphthalene and phenanthrene are generated. They play a key role in the proposed degradation–gasification mechanism since they are difficult to degrade and can lead to the formation of char. High-pressure SCW can more efficiently degrade and gasify such polymeric compounds compared to steam. Then, the supercritical fluid leads to the conversion of a greater amount of phenol into gas than steam: 68% of the pollutant is gasified at 750 bar and 700 °C after 16.5 min with no generation of pollutant by-products, except CO2. Furthermore, the gaseous stream contains the valuable green gases H2 and CH4. The use of highly compressed SCW implies not only the production of more gases but also the enrichment of the gas mixture in H2 and CH4. H2 and CH4 concentrations up to 35 and 30%, respectively, are obtained at 1000 bar.

Light polarization is a key factor of modern photonics. Tailoring surface plasmons (SPs) in anisotropically-shaped metallic nanostructures introduces the prospect of polarization control at small scale [1]. However, the resulting components remain much larger than the wavelength of light. Here, we present a travelling-wave helical plasmonic antenna (TW-HPA) that overcomes this limit [2]. Due to its non-resonant nature, it differs from existing helical plasmonic structures [3–5], thus extending the concept of travelling-wave helical antenna [6] to optics.

In this work, a versatile method is proposed to increase the sensitivity of optical sensors based on the localized surface plasmon resonance (LSPR) phenomenon. It combines a physical deposition method with the oblique angle deposition technique, allowing the preparation of plasmonic thin films with tailored porosity. Thin films of Au-TiO2 were deposited by reactive magnetron sputtering in a 3D nanostructure (zigzag growth), at different incidence angles (0° ≤ α ≤ 80°), followed by in-air thermal annealing at 400 °C to induce the growth of the Au nanoparticles. The roughness and surface porosity suffered a gradual increment by increasing the incidence angle. The resulting porous zigzag nanostructures that were obtained also decreased the principal refractive indexes (RIs) of the matrix and favoured the diffusion of Au through grain boundaries, originating broader nanoparticle size distributions. The transmittance minimum of the LSPR band appeared at around 600 nm, leading to a red-shift to about 626 nm for the highest incidence angle α = 80°, due to the presence of larger (scattering) nanoparticles. It is demonstrated that zigzag nanostructures can enhance adsorption sites for LSPR sensing by tailoring the porosity of the thin films. Atmosphere controlled transmittance-LSPR measurements showed that the RI sensitivity of the films is improved for higher incidence angles., This research was sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of Strategic Funding UID/FIS/04650/2013; project POCI-01-0145-FEDER-016902, with FCT reference PTDC/FIS-NAN/1154/2014; and project POCI-01-0145-FEDER-032299, with FCT reference PTDC/FIS-MAC/32299/2017. This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. Manuela Proença acknowledges her PhD grant from FCT, with reference SFRH/BD/137076/2018. Joel Borges acknowledges FCT for his Post-Doc grant SFRH/BPD/117010/2016. Marco S Rodrigues acknowledges FCT for his PhD grant with reference SFRH/BD/118684/2016. Konstantin Romanyuk wish to thank the Portuguese FCT for the financial support (grant SFRH/BPD/88362/2012)., info:eu-repo/semantics/publishedVersion

"Available online 08 April 2019", Nanocomposite thin films, composed of monometallic Au and Ag, and bimetallic AuAg nanoparticles, dispersed in a CuO matrix were prepared, characterised and tested for Localized Surface Plasmon Resonance (LSPR) sensing. The films were deposited by reactive magnetron sputtering, followed by a post-deposition thermal annealing to modify the size and shape of the nanoparticles distribution within the oxide matrix. Regarding the main results of the monometallic systems, the Au:CuO films showed LSPR bands from 800 nm to 650 nm, which reveal a progressive narrowing and a continuous blue-shift with increasing temperature (400–700 °C). The Ag:CuO films evidenced plasmonic bands at about 400 nm for temperatures of 500 °C and above. The bimetallic system, Au-Ag:CuO, showed LSPR bands in the range between those of the corresponding monometallic systems, due to the presence of Ag enriched AuAg alloy nanoparticles, taking part of Janus-like structures in some cases. In terms of LSPR sensing, Au:CuO films revealed the highest values of refractive index sensitivity since the nanoparticles are more exposed to the surrounding environment., This work was supported by the Portuguese Foundation for Scienceand Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019; and by the projects NANOSENSING, POCI-01-0145-FEDER-016902, with FCT reference PTDC/FIS-NAN/1154/2014; andNANO4BIO, POCI-01-0145-FEDER-032299, with FCT reference PTDC/FIS-MAC/32299/2017. Manuela Proença acknowledges her PhD grantfrom FCT, with reference SFRH/BD/137076/2018. Joel Borges ac-knowledges FCT for his Post-Doc grant SFRH/BPD/117010/2016.Marco S. Rodrigues acknowledges FCT for his PhD grant with referenceSFRH/BD/118684/2016. The authors would like to thank E. Alves(Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico,Universidade de Lisboa) and N. P. Barradas (Centro de Ciências eTecnologias Nucleares, Instituto Superior Técnico, Universidade deLisboa) for the RBS analysis., info:eu-repo/semantics/publishedVersion

International audience; Mg-Sn thin films (21 ≤ at. % Sn ≤ 42.5) were deposited by magnetron sputtering in the argon atmosphere. The structure and morphology of the films were characterized as a function of the composition. Mg2Sn structure was changed from stable face-centered cubic to metastable orthorhombic structure while the content of Sn in the films increased. The influence of this structural modification on thermoelectric properties was discussed in a wide range of temperatures (30–200 °C). The film carrier concentration and mobility were measured to explain the electronic transport behavior as a function of the film structural modifications. The maximum figure of merit ZT ≈ 0.26 at 200 °C was reached for the film with 36 at. % Sn while a mixture of cubic and orthorhombic Mg2Sn structures coexisted. An annealing treatment was performed under vacuum (∼10−4 Pa) at different temperatures (up to 600 °C) to determine the limit of structural and morphological stability of this film.

This work reports on the preparation and characterization of zigzag nanostructured silver (Ag) doped zinc oxide (ZnO) films in order to improve piezoresistive response for pressure sensor applications. ZnO/Ag thin films were prepared by Glancing Angle Deposition (GLAD) from a metallic zinc (Zn) target DC sputtered in Ar + O2 atmosphere. The target was customized with different amounts of Ag pellets, symmetrically distributed along the preferential erosion area. It is shown that increasing the Ag content from 0 to 36 at.% in the ZnO/Ag system leads to a decrease of the electrical resistivity from 2.95 Ω cm to 1.52 × 10−5 Ω cm. The structural characterization of the thin films shows an evolution of the preferential growth, changing from a polycrystalline ZnO hexagonal-like structure, confirmed by the presence of dominant ZnO (002) and ZnO (101) diffraction peaks, to a Ag cubic (fcc)-like structure, as evidenced by the Ag (111), (200) and (220) diffraction peaks. The values of the gauge factor show a strong contribution both from Ag as well as from the zigzag nanostructure to the piezoresistive sensitivity of the films, in particular for Ag concentrations lower than 30 at.%. The tunneling distance between pairs of Ag conductive nanoregions was calculated for the different samples and in three different deformation regions, in order to evaluate its influence on the piezoresistive sensitivity. The results show that a longer distance between Ag particles, which varies from 0.1 to 10 nm, enhances the gauge factor, which ranges from 8 ± 1 to 120 ± 3, respectively., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014. Armando Ferreira acknowledges the FCT for the SFRH/BPD/102402/2014 grant. Funding was also provided by the Region of Franche-Comté, the French RENATECH network. This work has also been supported by the EIPHI Graduate School (contract “ANR-17-EURE-0002”). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.

Inclined, zigzag and spiral Ti1-xCux films were co-sputtered by the Glancing Angle Deposition technique. Two distinct titanium (Ti) and copper (Cu) targets were used and the films were grown with a particle flow incidence angle α of 80°. The thin films had Cu contents ranging from 36 to 76 ± 5 at. %. The effect of increasing Cu incorporation on the electrical anisotropy, as well as the effect of columnar architecture variations on the morphological, structural and electrical properties of the films was evaluated and correlated with the particular their architectures. Main results show well-defined and highly inclined columns (with an average column angle β = 45° ± 5°) for all sputtering conditions. Quasi-amorphous thin films were obtained with low Cu contents (36 at. %), while crystalline Cu (111) + Ti3Cu (114) bi-component structures were achieved at high Cu concentrations (76 at. %). No permanent oxidation of the films was detected after a two-cycle RT-200 °C-RT (RT – room temperature) annealing in air. The two-dimensional representation of the resistivity anisotropy of the columnar and 2 zigzags films is shaped as an elongated ellipse along the xx direction, with a variation of the effective anisotropy, Aeff, at 200 °C from 1.4 to 2.9. The samples prepared with 2 spirals and the same Cu content (36 at. %) exhibit an isotropic behavior, with an Aeff value at 200 °C of 1.1. The overall results demonstrate the possibility to tune the thin films' morphology and electrical characteristics in order to obtain a set of properties that are suitable for the development of high performance materials, such as the case of resistance temperature detectors., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014. Armando Ferreira acknowledges the FCT for the SFRH/BPD/102402/2014 grant. Funding was also provided by the Region of Franche-Comte, the French RENATECH network and performed in cooperation with the Labex ACTION Program (contract ANR-11-LABX-01-01). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.

International audience; Tungsten oxide thin films exhibiting an oriented columnar architecture were prepared by reactive co-sputtering. Two opposite W and WO3 targets focused on the center of the substrate were simultaneously sputtered using opposite and oblique angles of 80° from the substrate normal. The reactive gas pulsing process was used to adjust the films electrical resistivity. Different inclined columnar structures were produced and applied as gas sensors for dodecane detection. Morphology, structure and resistivity of the films were investigated and connected to the sensing performances measured from 373 to 773 K.

International audience; We report on experimental investigations of electrical resistivity and surface elastic wave propagation in W and Au thin films sputter-deposited by glancing angle deposition. For both metals, the angle of deposition α is systematically changed from 0 to 85°. Dense and compact films are produced with a normal incident angle α=0°, whereas inclined and porous columnar architectures are clearly obtained for the highest angles. Group velocities and DC electrical resistivities of W and Au films are significantly changed in x and y directions as α increases from 0 to 85°. Isotropic behaviors are always observed for Au films, whereas anisotropic velocity and resistivity are clearly measured in W films prepared with incident angles higher than 60°. The anisotropic coefficient reaches 1.8 for velocity and 2.0 for resistivity in W films, while it remains in-between 1.0 and 1.2 in Au films whatever the incident angle. This directional dependence of electrical resistivity and elastic wave propagation is connected to the anisotropic structural characteristics of W inclined columns (fanning of their cross-section), while Au columns exhibit a more symmetric growth as a function of the incident angle.

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Pure V thin films were dc sputtered with different pressures (0.4 and 0.6 Pa) and particle incident angles α of 0°, 20° and 85°, by using the GLancing Angle Deposition (GLAD) technique. The sputtered films were characterized regarding their electrical resistivity behaviour in atmospheric pressure and in-vacuum conditions as a function of temperature (40–550 °C), in order to control the oxidation process. Aiming at comprehending the oxidation behaviour of the samples, extensive morphological and structural studies were performed on the as-deposited and annealed samples. Main results show that, in opposition to annealing in air, the columnar nanostructures are preserved in vacuum conditions, keeping metallic-like electrical properties.

Intrinsic differences in the molecular sequestration of folded and unfolded proteins within poly(diallyldimethylammonium) (PDDA)/poly(acrylate) (PAA) coacervate microdroplets are exploited to establish membrane-free microcompartments that support protein refolding, facilitate the recovery of secondary structure and enzyme activity, and enable the selective uptake and exclusion of folded and unfolded biomolecules, respectively. Native bovine serum albumin, carbonic anhydrase, and α-chymotrypsin are preferentially sequestered within positively charged coacervate microdroplets, and the unfolding of these proteins in the presence of increasing amounts of urea results in an exponential decrease in the equilibrium partition constants as well as the kinetic release of unfolded molecules from the droplets into the surrounding continuous phase. Slow refolding in the presence of positively charged microdroplets leads to the resequestration of functional proteins and the restoration of enzymatic activity; however, fast refolding results in protein aggregation at the droplet surface. In contrast, slow and fast refolding in the presence of negatively charged PDDA/PAA droplets gives rise to reduced protein aggregation and misfolding by interactions at the droplet surface to give increased levels of protein renaturation. Together, our observations provide new insights into the bottom-up design and construction of self-assembling microcompartments capable of supporting the selective uptake and refolding of globular proteins.

This paper presents results from an experimental study of three types of non-woven preforms (needlepunched, spunlaced and mat manufactured using a paper-making process) intended as composite reinforcement. These are potentially very attractive for transport applications. First, the influence of processing on elementary fiber tensile properties is shown to be limited. Then the preforms are evaluated in polypropylene matrix composites and mechanical properties are determined. The structure of non-woven reinforcements is strongly dependent on the manufacturing route. By varying the fiber content it is shown that the most efficient reinforcement for flax fibers is the mat produced by paper processing. The new spunlaced reinforced composites are shown to have slightly lower tensile properties (15% lower strength, and 25% lower stiffness) compared to mat composites at equivalent volume fraction, but further optimization is possible for these materials. Based on the measured constituent properties micromechanics models have been used to estimate composite stiffness. A good correlation is obtained between test results and model predictions.

Flexible polyurethane substrates were coated with Ag:TiN thin films (N/Ti atomic ratio = 0.7; 10 at.% Ag), with different column inclinations (α = 0°, 40° and 80°) and architectures (columnar, zigzag with 2 and 4 periods), using the Glancing Angle Deposition (GLAD) technique. The coatings were characterized in order to assess the best thin film architecture to suit the bio-potential electrode applications. An abrupt increase of porosity of the samples was perceivable with increasing α angles (particularly from 40° to 80°). Hence, the sputtered films could be divided into dense (Ag:TiN 0° and Ag:TiN 40°) and porous (Ag:TiN 80°, Ag:TiN 80° 2Z and Ag:TiN 80° 4Z) samples. The electrochemical behaviour of the sampleswas consistently linked to the porosity differences,which was accompanied by an increase of the surface Ag content. Furthermore, the porous samples exhibited lower impedances (~104 Ωcm2 at 2 MHz), as well as electrochemical noise and drift rate values similar to those of the commercial Ag/AgCl electrodes. Hence, the porous Ag:TiN 80°, Ag:TiN 80° 2Z and Ag:TiN 80° 4Z porous Ag:TiN GLAD coatings seem to be the most promising architectures for the envisaged bio-potential electrode applications., This research is partially sponsored by FEDER funds through the programme COMPETE - Programa Operacional Factores de Competitividade, by national funds through FCT – Fundação para a Ciência e a Tecnologia, under the projects PEst-C/EME/UI0285/2011, PTDC/SAU-ENB/116850/2010, PTDC/CTM-NAN/112574/2009 and Programa Pessoa 2012/2013 Cooperação Portugal/França, Project no. 27306UA Porous architectures in GRAded CERamic thin films for biosensors — GRACER. The authors would also like to acknowledge to the European Union (FP7-PEOPLE Marie Curie IAPP, project 610950), to CEMUP for SEM analysis and Yantai Wanhua Polyurethanes Co., Ltd. for providing the thermoplastic polyurethane pellets. P. Pedrosa acknowledges FCT for the Ph.D. grant SFRH/BD/70035/2010.

This manuscript describes a kinetic and mechanistic study of the gasification with water of two carbonized materials originating from a phenolic textile fiber and holm oak wood at 540–650 °C and 1–1000 bar. The wide experimental range studied causes the number of hydrogen bonds to strongly vary with the gasifying conditions, which generates important changes in the structure and properties of water. The solvent–solvent and solvent–solute interactions are significantly affected, with pressure favoring the formation of clusters. The concentration of the gas produced and the kinetics and pathways of gasification show a strong dependence on pressure. The study reveals the importance of the oxygen surface groups in gasification. These groups take part in some pathways of the gasification and control the gasification rate and the concentration of the gases. The formation of clusters of water molecules on the oxygen surface groups at high pressures enables a new pathway that accelerates the gasification and guides it toward the direct formation of CO 2 . Although gasification is accelerated by pressure, increasing amounts of the H 2 produced are readsorbed onto the active sites of the solid, disabling them from being gasified (auto-inhibition phenomenon). Consequently, a pressure within this range yields the highest gasification rate.

This study investigates the role of acetone, as a carrier for nano-hydroxyapatite (nano-HA) in solution, to enhance the infiltration of fully demineralized dentin with HA nanoparticles (NPs).Dentin specimens were fully demineralized and subsequently infiltrated with two types of water-based nano-HA solutions (one containing acetone and one without). Characterization of the dentin surfaces and nano-HA particles was performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface wettability and infiltration capacity of the nano-HA solutions were quantified by means of contact angle measurements and energy dispersive X-ray spectroscopy (EDS), respectively. Contact angle measurements were taken at baseline and repeated at regular intervals to assess the effect of acetone. The P and Ca levels of infiltrated dentin specimens were measured and compared to sound dentin and non-infiltrated controls.The presence of acetone resulted in an eight-fold decrease in the contact angles of the nano-HA solutions recorded on the surface of demineralized dentin compared to nano-HA solutions without acetone (one-way ANOVA, p0.05). Perfect wetting of the demineralized dentin surface was achieved 5min after the application of the nano-HA solution containing acetone. Infiltration of demineralized dentin with the nano-HA solution containing acetone restored the lost mineral content by 50%, whereas the mean mineralization values for P and Ca in dentin treated with the acetone-free nano-HA solution were less than 6%.Acetone was shown to act as a vehicle to enhance the capacity to infiltrate demineralized dentin with HA NPs. The successful infiltration of dentin collagen with HA NPs provides a suitable scaffold, whereby the infiltrated HA NPs have the potential to act as seeds that may initiate heterogenous mineral growth when exposed to an appropriate mineral-rich environment.

This work reports for the first time a treatment to manage engine oils in an environmentally friendly manner which, besides, upgrades them into valuable gases: gasification with steam and supercritical water (SCW). Pressure, temperature and wt% ranges from 50 to 500 bar, 500–800 °C and 0.42–2.0%, respectively, were investigated. The process can be faced in two different ways regarding the temperature. A low-temperature gasification at 550 °C to transform up to 60% of oil into carbon-containing gases such as CH4 and ethane in less than 2 min; and a high-temperature gasification at 750 °C that produces H2, CH4 and CO2 as main gaseous products. Namely, SCW gasification at 250 bar, 750 °C and 0.83 wt% for 1.9 min transformed more than 85% of the oil into a gaseous mixture containing 37% H2 and 29% CH4, two valuable green fuels. The treatment is herein used to upgrade fresh engine oils but it is potentially applicable to the upgrading of such an abundant and polluting residue as waste engine oils.

© 2020 by the authors., This Special Issue contains a series of reviews and papers representing some recent results and some exciting perspectives focused on advanced strategies in thin films growth, thin films engineering by magnetron sputtering and related techniques. Innovative fundamental and applied research studies are then reported, emphasizing correlations between structuration process parameters, new ideas and approaches for thin films engineering and resulting properties of as-deposited coatings.

Objective\ud \ud To compare the fatigue strength of lithium disilicate ceramic crowns when cemented as a compound structure, as a function of the manufacturing process and the type of ceramic variation.\ud \ud \ud \ud Method\ud \ud A typodont maxillary first premolar was prepared for an all-ceramic crown in accordance with the manufacturer's guidelines for monolithic ceramic crowns (IPS e. max®; Ivoclar-Vivadent, Liechtenstein). 60 dies were duplicated in a polymer with a Young's Modulus closely matched to dentine (Alpha die, Schütz GmbH). Three different crown fabrication techniques were used (n = 20): (i) Manually applied wax spacer and pressed-crown; (ii) digitally scanned preparation, CAD-printed wax-pattern (D76PLUS, Solidscape Inc.) and pressed-crown; (iii) digitally scanned preparation and machined-crown (CEREC-inLab® v3.6 Sirona GmbH). Resin-based cement (Variolink-II®, Ivoclar-Vivadent, Liechtenstein) was employed with a standardised mechanised cementation technique to apply a controlled axial cementation pressure [Universal testing machine (Lloyd LRX®, Lloyd Materials Testing Inc)]. The samples were subjected to fatigue life testing with a cyclic impact load of 453 N for 1.25 × 106cycles at 37C⁰ and 1 Hz frequency until the point of fracture.\ud \ud \ud \ud Result\ud \ud There was a significant difference in the resistance to fatigue loading between the three groups. Weibull probability analysis and the α and β Weibull parameters indicate that the teeth restored with a ‘Manually-applied wax spacer and pressed-crown’ are best able to resist cyclic fatigue loading. They also have the most uniform interface geometry.\ud \ud \ud \ud Conclusion\ud \ud Teeth restored with IPS e. max® crowns constructed by manually applied wax spacer and pressing, have a more uniform interface and a greater structural integrity than wax CAD-printed patterns or CAD-CAM crowns.

Tungsten films were prepared by DC magnetron sputtering using glancing angle deposition with a constant deposition angle &alpha, = 80&deg, A first series of films was obtained at a constant pressure of 4.0 &times, 10&minus, 3 mbar with the films&rsquo, thickness increasing from 50 to 1000 nm. A second series was produced with a constant thickness of 400 nm, whereas the pressure was gradually changed from 2.5 &times, 3 to 15 &times, 3 mbar. The A15 &beta, phase exhibiting a poor crystallinity was favored at high pressure and for the thinner films, whereas the bcc &alpha, phase prevailed at low pressure and for the thicker ones. The tilt angle of the columnar microstructure and fanning of their cross-section were tuned as a function of the pressure and film thickness. Electrical resistivity and surface elastic wave velocity exhibited the highest anisotropic behaviors for the thickest films and the lowest pressure. These asymmetric electrical and elastic properties were directly connected to the anisotropic structural characteristics of tungsten films. They became particularly significant for thicknesses higher than 450 nm and when sputtered particles were mainly ballistic (low pressures). Electronic transport properties, as well as elastic wave propagation, are discussed considering the porous architecture changes vs. film thickness and pressure.

Thin films of (CoCrCuFeNi) N x were deposited by direct current reactive magnetron sputtering. Two different targets were used. Thin films deposited from a solid near-equimolar target showed a Cu excess with segregation of Cu in the film resulting in the formation of a nanocomposite film. It was also not possible to reach fully stoichiometric nitride thin films with this target. To overcome this problem, a powder target with adjusted composition was used in a second series of experiments. As derived from longitudinal and transversal sound velocity measurements, a transition from the metallic face-centred cubic lattice to the nitride B1 (NaCl) structure is observed. The observed transition corresponds with the process change from the metallic regime at low nitrogen partial pressure to the poisoned regime at high nitrogen partial pressure. TEM measurements show a typical zone T growth with a strong (100) texture in the nitride regime, and reveal a mixing of the constituent metals at the nanometer scale. This study demonstrates that the constituent metals do not form binary nitrides, but a complex nitride is formed.

UMR BFP - Equipe Mollicutes; International audience; We describe the fabrication of stable colloidosomes derived from water-in-water Pickering-like emulsions produced by addition of fluorescent amine-modified polystyrene latex beads to an aqueous two-phase system consisting of dextran-enriched droplets dispersed in a PEG-enriched continuous phase. Addition of polyacrylic acid followed by carbodiimide-induced crosslinking with dextran produces hydrogelled droplets capable of reversible swelling and selective molecular uptake and exclusion. Colloidosomes produced specifically in all-water systems could offer new opportunities in microencapsulation and the bottom-up construction of synthetic protocells.

The properties of supercritical CO2 (SCCO2) and supercritical water (SCW) turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF) saturated with a pollutant usually contained in wastewater and drinking water, phenol. Severe regeneration conditions, up to 225 bar and 400 °C, had to be employed in SCCO2 regeneration to break the strong interaction established between phenol and the ACF. Under suitable conditions (regeneration temperature, time, and pressure, and flow of SCCO2) the adsorption capacity of the exhausted ACF was completely recovered, and even slightly increased. Most of the retained phenol was removed by thermal desorption, but the extra percentage removed by extraction allowed SCCO2 regeneration to be significantly more efficient than the classical thermal regeneration methods. SCCO2 regeneration and SCW regeneration were also compared for the first time. The use of SCW slightly improved regeneration, although SCW pressure was thrice SCCO2 pressure. The pathways that controlled SCW regeneration were also investigated.

International audience; wo series of W-Cu thin films were developed by the GLAD co-sputtering technique. The films were produced with two separated W and Cu targets. Both targets were focused on the centre of the substrate and were simultaneously sputtered using opposite and oblique angles of 80° from the substrate normal. In the first series, the W and Cu target currents were inversely changed from 50 to 140. mA in order to tune the elemental concentrations and the microstructure. For the second series, a shield was added between W and Cu targets, perpendicularly to the substrate surface in order to prevent the cross-contamination of the targets. The target currents were varied similarly to the first series. Two argon sputtering pressures were used (0.42 and 1.0. Pa) in each series, with and without the shield.Microstructure showed a tuneable inclined columnar microstructure, which become normal to the substrate at high pressure. The crystallographic structure was not significantly influenced by the shield implementation but rather by the sputtering pressure. The W/Cu atomic concentration ratio varied between 0.2 and 5.5 as a function of the sputtering pressure and target currents and an anisotropic chemical composition was measured inside the columns. The wide range of DC electrical resistivities (3.6×10⁻⁷ to 5.7×10⁻⁵ Ωm) was discussed considering W and Cu target currents, high and low sputtering pressures and the use of a cross-contamination shield. The role of the microstructure was clearly shown since significantly higher resistivity was obtained at high pressure, as a function of the W/Cu atomic concentration ratio. W-Cu sputtered thin films grown at... (PDF Download Available). Available from: https://www.researchgate.net/publication/320080270_W-Cu_sputtered_thin_films_grown_at_oblique_angles_from_two_sources_Pressure_and_shielding_effects [accessed Apr 09 2018].

Mg&ndash, Si thin films (23 &le, at.% Si &le, 43) were deposited by co-sputtering of Mg and Si targets in an argon atmosphere. Two groups of samples were prepared with respect to sputtering parameters. The first Group I was synthesized while residual pressure in the reactor was lower than 7 &times, 10&minus, 4 Pa and the second Group II when reactor was pumped down to pressure higher than 7 &times, 4 Pa. The Mg2Si phase appeared for all as-deposited films of Group I around the stoichiometric composition region (29 &le, 37) and in the Mg-rich region (at.% Si &lt, 29) the Mg2Si and Mg phases coexisted. An amorphous structure was obtained for all as-deposited films of Group II no matter their composition (34 &le, 38) and the Mg2Si structure was achieved after post annealing under air at temperature &ge, 140 &deg, C. Thermal stability of Mg2Si thin films was investigated by annealing treatments under air. Superficial Mg2Si structural decomposition began at T &gt, 500 &deg, C and layer morphology and structure damaged while annealing temperature increased up to 700 &deg, C. The films&rsquo, electrical resistivity, free carrier concentration and mobility as well as Seebeck coefficient were measured and thermoelectric power factors were discussed vs. composition.

International audience; Nanomaterials based on Localized Surface Plasmon Resonance (LSPR) phenomena are revealing to be an important solution for several applications, namely those of optical biosensing. The main reasons are mostly related to their high sensitivity, with label-free detection, and to the simplified optical systems that can be implemented. For the present work, the optical sensing capabilities were tailored by optimizing LSPR absorption bands of nanocomposite Au/TiO2 thin films. These were grown by reactive DC magnetron sputtering. The main deposition parameters changed were the number of Au pellets placed in the Ti target, the deposition time, and DC current applied to the Ti-Au target. Furthermore, the Au NPs clustering, a key feature to have biosensing responses, was induced by several post-deposition in-air annealing treatments at different temperatures, and investigated via SEM analysis. Results showed that the Au/TiO2 thin films with a relatively low thickness (similar to 100 nm), revealing concentrations of Au close to 13 at.%, and annealed at temperatures above 600 degrees C, had the most well-defined LSPR absorption band and thus, the most promising characteristics to be explored as optical sensors. The NPs formation studies revealed an incomplete aggregation at 300 and 500 degrees C and well-defined spheroidal NPs for higher temperatures. Plasma treatment with Ar led to a gradual blue-shift of the LSPR absorption band, which demonstrates the sensitivity of the films to changes in the dielectric environment surrounding the NPs (essential for optical sensing applications) and the exposure of the Au nanoparticles (crucial for a higher sensitivity). (C) 2017 Elsevier B.V. All rights reserved.

Density is one of the fundamental properties of fibres which reinforce polymer matrix composites, and is used both to estimate composite weight and to evaluate fibre content for property predictions. For traditional composites, reinforced by glass or carbon fibres, unique density values are well known for a particular fibre grade and provide reliable fibre content estimations and composite property predictions. However, this is not the case for natural fibres. This paper first reviews published density values for flax (Linum usitatissimum L.) fibres and describes the limitations of techniques used to measure fibre density. Significant variations in published densities are found, which can be related to the measurement method. New data quantify the influence of measurement technique, fibre extraction route, moisture content, and reinforcement geometry. Values obtained by buoyancy are around 10% lower than those obtained by pycnometry. Finally the consequences of measured density variations on property estimations for long fibre composites are discussed; volume fraction values calculated from buoyancy provide more accurate tensile modulus values compared to experimental values than those from gas pycnometry; the former are recommended for predictive use.

This work reports on the preparation and characterization of Zinc Oxide (ZnO) thin films, exploring their anisotropic electrical resistivity behaviour evolution as a function of the different preparation conditions. Results show that by increasing the oxygen content in the work gas flow, the electrical resistivity increases from about 2.4 x 10(-2) Omega.cm (common in fairly conductive-like materials) to values in order of M Omega.cm, which is typical of materials that vary from semiconducting to roughly insulating type. Regarding the thin films structural behaviour, a relatively clear evolution of the preferential growth becomes clear when preparing the films within the three different regimes. The X-ray diffraction (XRD) patterns revealed the development of a polycrystalline hexagonal-like structure, confirmed by the presence of dominant and very intense ZnO (002) and ZnO (101) diffraction peaks. A change in preferential growth was noticed with the change in the preparation conditions.By in-air annealing the samples from room temperature (RT) up to 200 degrees C and cooling down to RT again, the differences between the resistivity values along the xx and yy directions become significant, a clear sign of the anisotropic nature of the films. The anisotropy obtained during the annealing cycles of the films increased from 0.98 to 1.10 and, consequently, the Temperature Coefficient of Resistance, TCR, increased in both xx and yy directions, from TCRxx (and yy) similar to 9.0x10(-4) to TCRxx = 6.82 x 10(-3) and TCRyy = 5.97 x 10(-3) degrees C-1. Important also to note is that the increase of the grain size of the films showed to have a significant effect in the effective anisotropy, revealing to be a major factor to take into account., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014 and by the Region of Franche-Comte, the French RENATECH network and performed in cooperation with the Labex ACTION program (contract ANR-11-LABX-01-01). A. Ferreira thanks the FCT for grant SFRH/BPD/102402/2014. Financial support from the Basque Government Industry Department under the ELKARTEK Program is also acknowledged., info:eu-repo/semantics/publishedVersion

International audience; Two immiscible metals (W and Cu) were deposited using two metallic targets by GLAD co-sputtering. A wet chemical etching technique was implemented to remove the copper and modify the typical inclined microstructure into a more porous architecture. The electrical resistivity behavior of the co-sputtered W-Cu film was characterized as a function of temperature before and after wet chemical etching. The results show that the columnar microstructure exhibits metallic-like electrical properties. The average DC electrical resistivity ρ changes from 1.66 × 10−5 Ωm to 4.28 × 10−5 Ωm after etching. The anisotropy at room temperature is A = 1.8 ± 0.1 for as-deposited W-Cu film and reaches 2.8 ± 0.1 after the etching procedure.